CN105316083B

CN105316083B - Lubricating oil composition

Info

Publication number: CN105316083B
Application number: CN201510292265.8A
Authority: CN
Inventors: A·J·斯特朗; P·J·伍德沃德
Original assignee: Infineum International Ltd
Current assignee: Infineum International Ltd
Priority date: 2014-06-02
Filing date: 2015-06-01
Publication date: 2020-07-03
Anticipated expiration: 2035-06-01
Also published as: GB201509513D0; JP2015227453A; GB2528374A; EP2952563B1; CA2893426A1; CA2893426C; SG10201504243SA; CN105316083A; BR102015012734A2; EP2952563A1; BR102015012734B1; JP6669442B2; US20150344812A1

Abstract

A lubricating oil composition having a sulfated ash content of less than or equal to 1.2 mass%, as determined by ASTM D874, and a phosphorus content of less than or equal to 0.12 mass%, as determined by ASTM D5185, comprising or prepared by admixing: a major amount of an oil of lubricating viscosity; an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier as an additive; and an effective minor amount of an oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate metal salt as an additive.

Description

Lubricating oil composition

Technical Field

The present invention relates to automotive lubricating oil compositions. More particularly, although not exclusively, the invention relates to automotive crankcase lubricating oil compositions for gasoline (spark-ignited) and diesel (compression-ignited) internal combustion engines, such compositions being referred to as crankcase lubricants; and to the use of additives in such lubricating oil compositions to improve the anti-corrosion properties (i.e., inhibit corrosion of non-ferrous metal engine components) with respect to non-ferrous metal engine components, particularly engine components (e.g., bearings) containing copper and/or lead.

Background

Crankcase lubricants are oils used for general lubrication in internal combustion engines, where an oil tank is usually located below the crankshaft of the engine and where circulating oil is returned.

Antiwear agents are commonly used as additives in crankcase lubricants to reduce excessive wear of metal engine components. Such antiwear agents are typically based on sulfur-or phosphorus-or both-containing compounds, such as compounds capable of depositing polysulfide films on the surfaces of metal engine components. A common antiwear agent routinely used in crankcase lubricants is a dihydrocarbyl dithiophosphate metal salt.

It would also be desirable to reduce the energy and fuel consumption requirements of an engine, and therefore a crankcase lubricant that reduces the overall friction of the engine would also be desirable. Reducing friction losses in an engine generally contributes significantly to improving the fuel economy performance and fuel economy retention performance of the engine. Thus, it has long been known to use ashless organic friction modifiers, such as ashless, nitrogen-free organic friction modifiers (e.g., esters formed from carboxylic acids and alkanols, such as Glycerol Monooleate (GMO)), as additives in crankcase lubricants to obtain improved friction performance and improved fuel economy performance.

Thus, to provide crankcase lubricants with desired antiwear properties and desired friction properties, lubricating oil formulators typically use dihydrocarbyl dithiophosphate metal salt antiwear additives in combination with ashless organic friction modifier additives such as GMO in lubricating oil compositions.

It has now been found that the use of ashless organic friction modifier additives such as GMO in lubricants generally produces significant amounts of lead and copper corrosion. In addition, the amount of lead corrosion is generally further increased when ashless organic friction modifier additives such as GMO are used in combination with dihydrocarbyl dithiophosphate metal salt anti-wear additives. The corrosion properties of ashless organic friction modifier additives such as GMO and the increased lead corrosion attributable to the ashless organic friction modifier additive in combination with the dihydrocarbyl dithiophosphate metal salt present problems for lubricating oil formulators. For example, particularly when used in combination, the corrosive nature of the additive components may necessitate reduced additive treat rates, thereby affecting the antiwear and/or fuel economy performance of the lubricant; alternatively or additionally, other more expensive anti-corrosion additives may have to be included in the lubricant to combat the corrosion properties of the dihydrocarbyl dithiophosphate metal salts and ashless organic friction modifier additives.

Accordingly, there is a need for lubricating oil compositions comprising metal dihydrocarbyl dithiophosphate antiwear agents and ashless organic friction modifier additives that exhibit improved corrosion resistance in non-ferrous metal engine components, particularly those containing copper and/or lead or alloys thereof.

Summary of The Invention

According to a first aspect, the present invention provides a lubricating oil composition having a sulphated ash content of less than or equal to 1.2 mass%, as determined by ASTM D874, and a phosphorus content of less than or equal to 0.12 mass%, as determined by ASTM D5185, comprising or prepared by admixing:

(A) a major amount of an oil of lubricating viscosity;

(B) an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier as an additive, the polymeric friction modifier being the reaction product of only:

(i) a functionalized polyolefin;

(ii) a polyalkylene glycol;

(iii) a polyol; and

(iv) a polycarboxylic acid;

and

(C) an effective minor amount of at least one oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate as an additive.

Preferably, the lubricating oil composition of the present invention is a crankcase lubricant.

It has unexpectedly been found that the use of an effective minor amount of a polymeric friction modifier (B) as defined according to the first aspect of the present invention as an additive in a lubricating oil composition comprising a major amount of an oil of lubricating viscosity can inhibit corrosion of engine components comprising non-ferrous metals, such as copper and/or lead, compared to a comparative lubricant not comprising the polymeric friction modifier (B). In other words, the polymeric friction modifier (B) may act as an anti-corrosion agent in engine components containing non-ferrous metals, particularly engine components containing copper and/or lead or alloys containing such metals.

Furthermore, it has been found that the use of an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in the first aspect of the invention as an additive in combination with an effective minor amount of an oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate as defined in the first aspect of the invention as an additive in a lubricating oil composition comprising a major amount of an oil of lubricating viscosity generally provides a lubricant that exhibits improved corrosion inhibition and/or reduction (i.e. inhibition of corrosion) of engine components comprising non-ferrous metals (e.g. copper and/or lead) compared to a comparative lubricant comprising an ashless organic friction modifier (e.g. GMO) in combination with an oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate as defined in the first aspect of the invention.

Still further, it has been found that the use of an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in the first aspect of the present invention as an additive in combination with an effective minor amount of an oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate metal salt as an additive in a lubricating oil composition comprising a major amount of an oil of lubricating viscosity generally provides a lubricant that exhibits improved corrosion inhibition and/or reduction (i.e. inhibition of corrosion) of copper-containing metal engine components as compared to the following comparative lubricants: (i) a comparative lubricant comprising a dihydrocarbyl dithiophosphate metal salt and no polymeric friction modifier (B); and (ii) a comparative lubricant that does not contain the dihydrocarbyl dithiophosphate metal salt and the polymeric friction modifier (B).

Thus, the reduced non-ferrous metal corrosion levels (e.g., reduced copper and/or lead corrosion levels) associated with the use of the polymeric friction modifier (B) may allow for increased treat rates of such additive combinations in lubricants as compared to ashless organic friction modifiers such as GMO, particularly when used in combination with dihydrocarbyl dithiophosphate metal salts. Additionally or alternatively, the reduced non-ferrous metal corrosion level may reduce the need to use more expensive supplemental anti-corrosion additives. Thus, the use of polymeric friction modifiers (B) in combination with dihydrocarbyl dithiophosphate metal salts generally provides the formulator with a greater degree of flexibility in formulating lubricating oil compositions that must meet stringent anti-wear performance and fuel economy performance standards as set forth in the specifications of the industrial lubricating oil and original equipment manufacturers.

According to a second aspect, the present invention provides a method of lubricating a spark-ignited or compression-ignited internal combustion engine, said method comprising lubricating the engine with a lubricating oil composition as defined in accordance with the first aspect of the present invention.

According to a third aspect, the present invention provides the use of an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in the first aspect of the invention as an additive in the lubrication of a spark-ignited or compression-ignited internal combustion engine to reduce and/or inhibit corrosion (i.e. inhibit corrosion) of non-ferrous metal containing engine components during operation of the engine in a lubricating oil composition comprising a major amount of an oil of lubricating viscosity. Suitably, the engine component comprising a non-ferrous metal comprises copper, lead or an alloy of such metals.

Suitably, the lubricating oil composition as defined in the third aspect of the present invention further comprises as an additive an effective minor amount of a dihydrocarbyl dithiophosphate metal salt as defined in the first aspect of the present invention.

According to a fourth aspect, the present invention provides the use of an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in the first aspect of the invention as an additive in combination with an effective minor amount of an oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate (C) as defined in the first aspect of the invention as an additive in a lubricating oil composition comprising a major amount of an oil of lubricating viscosity to reduce and/or inhibit corrosion (i.e. inhibit corrosion) of engine components containing nonferrous metals during operation of the engine in the lubrication of a spark-ignited or compression-ignited internal combustion engine. Suitably, the engine component comprising a non-ferrous metal comprises copper, lead or an alloy of such metals, especially copper or an alloy thereof.

According to a fifth aspect, the present invention provides the use of a lubricating oil composition according to the first aspect of the present invention to reduce and/or inhibit corrosion (i.e. inhibit corrosion) of non-ferrous metal containing engine components during operation of the engine in the lubrication of a spark-ignited or compression-ignited internal combustion engine. Suitably, the engine component comprising a non-ferrous metal comprises copper, lead or an alloy of such metals, especially copper or an alloy thereof.

According to a sixth aspect, the present invention provides a method of inhibiting and/or reducing corrosion (i.e. inhibiting corrosion) of a non-ferrous metal containing engine component of an engine, the method comprising lubricating the engine with a lubricating oil composition comprising as an additive a major amount of an oil of lubricating viscosity and an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in the first aspect of the invention, and operating the engine. Suitably, the engine component comprising a non-ferrous metal comprises copper, lead or an alloy of such metals. Suitably, the engine as defined in the sixth aspect of the present invention is a spark-ignition or compression-ignition internal combustion engine.

According to a seventh aspect, the present invention provides a method of inhibiting and/or reducing corrosion (i.e. inhibiting corrosion) of a non-ferrous metal containing engine component of an engine, said method comprising lubricating the engine with a lubricating oil composition according to the first aspect of the present invention, and operating the engine. Suitably, the engine component comprising a non-ferrous metal comprises copper, lead or an alloy of such metals, especially copper or an alloy thereof. Suitably, the engine as defined in the seventh aspect of the present invention is a spark-ignition or compression-ignition internal combustion engine.

Preferably, the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate (C) is an oil-soluble or oil-dispersible zinc dihydrocarbyl dithiophosphate (i.e., Zinc Dihydrocarbyl Dithiophosphate (ZDDP)), more preferably an oil-soluble or oil-dispersible zinc dialkyl dithiophosphate.

Preferably, the lubricating oil composition of the first aspect of the present invention and as defined in the second, third, fourth, fifth, sixth and seventh aspects of the present invention further comprises an effective minor amount (0.1 to 30 mass%) of one or more co-additives other than additive components (B) and (C), said co-additives being selected from ashless dispersants, metallic detergents, corrosion inhibitors, antioxidants, pour point depressants, antiwear agents, friction modifiers, demulsifiers, antifoamants and viscosity modifiers.

The lubricating oil composition of the present invention has a sulfated ash content of less than or equal to 1.2 mass%, preferably less than or equal to 1.1 mass%, more preferably less than or equal to 1.0 mass% (ASTM D874), based on the total mass of the composition.

Preferably, the lubricating oil compositions of the present invention comprise a low phosphorus content. The lubricating oil composition comprises phosphorus in an amount of less than or equal to 0.12 mass%, preferably at most 0.11 mass%, more preferably less than or equal to 0.10 mass%, even more preferably less than or equal to 0.09 mass%, even more preferably less than or equal to 0.08 mass%, most preferably less than or equal to 0.06 mass% phosphorus (ASTM D5185), based on the total mass of the composition. Suitably, the lubricating oil composition comprises phosphorus in an amount of greater than or equal to 0.01 mass%, preferably greater than or equal to 0.02 mass%, more preferably greater than or equal to 0.03 mass%, even more preferably greater than or equal to 0.05 mass% phosphorus (ASTM D5185), based on the total mass of the composition.

Typically, the lubricating oil compositions of the present invention may comprise low sulfur content. Preferably, the lubricating oil composition comprises sulfur in an amount of up to 0.4 mass%, more preferably up to 0.3 mass%, even more preferably up to 0.2 mass% sulfur (astm d2622), based on the total mass of the composition.

Typically, the lubricating oil composition of the present invention comprises at most 0.30 mass%, more preferably at most 0.20 mass%, most preferably at most 0.15 mass% nitrogen, based on the total mass of the composition and measured according to ASTM method D5291.

Suitably, the lubricating oil composition may have a Total Base Number (TBN) of from 4 to 15mg KOH/g, preferably from 5 to 12mg KOH/g, measured according to ASTM D2896.

In the present specification, the following expressions and expressions, if and when used, have the meanings given below:

"active ingredient" or "(a.i.)" refers to an additive material that is not a diluent or solvent;

"comprises," "comprising," or any other variation thereof describes the presence of stated features, steps, or integers or components, but does not preclude the presence or addition of one or more other features, steps, integers, components, or groups thereof. The expression "consisting of …" or "consisting essentially of …" or the like may be included within the expression "comprising" or the like, wherein "consisting essentially of …" allows the inclusion of substances that do not substantially affect the characteristics of the composition in which it is used;

"hydrocarbyl" means a chemical group of a compound that contains hydrogen and carbon atoms and is bonded directly to the remainder of the compound via a carbon atom. The group may contain one or more atoms other than carbon and hydrogen, provided that they do not affect the basic hydrocarbyl nature of the group. Those skilled in the art are familiar with suitable groups (e.g., halogens, especially chlorine and fluorine, amino, alkoxy, mercapto, alkylmercapto, nitro, nitroso, sulfinyl (sulfoxy), and the like). Preferably, unless otherwise specified, the group consists essentially of hydrogen and carbon atoms. Preferably, the hydrocarbon group comprises an aliphatic hydrocarbon group. The term "hydrocarbyl" includes "alkyl", "alkenyl", "allyl", and "aryl" as defined herein;

"alkylene" is synonymous with "alkanediyl" and means a C derived from an alkane by the removal of a hydrogen atom from two different carbon atoms₂-C₂₀Preferably C₂-C₁₀More preferably C₂-C₆A divalent saturated acyclic aliphatic hydrocarbon group; it may be linear or branched. Representative examples of alkylene groups include ethylene (ethylene glycol), propylene (propylene glycol), butylene (butylene glycol), isobutylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, 1-methylethylene, 1-ethylethylene, 1-ethyl-2-methylethylene, 1-dimethylethylene, and 1-ethylpropylene;

by "poly (alkylene)" is meant a polymer comprising suitable alkylene repeat units. Such polymers may be formed by polymerization of suitable olefins (e.g., polyisobutylene may be formed by polymerization of isobutylene);

"alkyl" means C directly bonded to the remainder of the compound via a single carbon atom₁-C₃₀An alkyl group. Unless otherwise described, when there is a sufficient number of carbon atoms, the alkyl group may be linear (i.e., unbranched) or branched, and may be cyclic, acyclic, or partially cyclic/acyclic. Preferably, the alkyl group comprises a linear or branched acyclic alkyl group. Representative examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, dimethylhexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, and triacontyl;

"alkynyl" means a C group containing at least one carbon-carbon triple bond and bonded directly to the remainder of the compound via a single carbon atom₂-C₃₀Preferably C₂-C₁₂Groups, and others are as defined for "alkyl";

"aryl" means a compound directly attached to the remainder of the compound via a single carbon atom, optionally substituted with one or more alkyl, halo, hydroxy, alkoxy, and amino groups，C₆-C₁₈Preferably C₆-C₁₀An aromatic group. Preferred aryl groups include phenyl and naphthyl and substituted derivatives thereof, especially phenyl and alkyl substituted derivatives thereof;

"alkenyl" means a C group containing at least one carbon-carbon double bond and bonded directly to the remainder of the compound via a single carbon atom₂-C₃₀Preferably C₂-C₁₂Groups, and others are as defined for "alkyl";

by "polyol" is meant an alcohol (i.e., a polyol) containing 2 or more hydroxyl functional groups, but excluding "polyalkylene glycols" (component b (ii)) used to form oil-soluble or oil-dispersible polymeric friction modifiers. More specifically, the term "polyol" includes diols, triols, tetrols (tetrols) and/or related dimers or chain-extended polymers of such compounds. Even more specifically, the term "polyol" includes glycerol, neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol;

"polycarboxylic acid" means an organic acid, preferably a hydrocarbyl acid, more preferably an aliphatic hydrocarbyl acid, comprising 2 or more carboxylic acid functional groups. The term "polycarboxylic acids" includes di-, tri-and tetracarboxylic acids;

"halo" or "halogen" includes fluorine, chlorine, bromine and iodine;

as used herein, "oil-soluble" or "oil-dispersible" or like terms do not necessarily indicate that the compound or additive may be soluble, dissolvable, miscible in oil, or capable of being suspended in all proportions. However, these means that they are, for example, soluble or stably dispersible in the oil to a sufficient extent to exert their intended effect in the environment in which the oil is used. Furthermore, additional incorporation of other additives may also allow for incorporation of high levels of particular additives, if desired;

"ashless" in relation to an additive means that the additive does not contain a metal;

"ash-containing" in connection with the additive means that the additive comprises a metal;

"major amount" means the amount of active ingredient calculated as a component, expressed in terms of the total mass of the component and in terms of the composition, in excess of 50% by mass of the composition;

"minor amount" means less than 50% by mass of the composition, calculated as active ingredient of the additive, expressed in relation to the additive and in relation to the total mass of the composition;

"effective minor amount" in relation to an additive means a minor amount of the additive in a lubricating oil composition such that the additive provides the desired technical effect;

"non-ferrous metals" include metals of lead, copper, tin or alloys thereof, or alloys of such metals, preferably copper or lead, or alloys of such metals, especially copper or alloys thereof;

nonferrous metal corrosion (e.g., copper and lead corrosion) was measured by the high temperature corrosion bench test according to ASTM D6594;

"ppm" means parts by mass per million parts by mass based on the total mass of the lubricating oil composition;

the "metal content" of a lubricating oil composition or additive component, such as the molybdenum content or total metal content (i.e., the sum of all of the various metal contents) of a lubricating oil composition, is measured by ASTM D5185;

"TBN" in relation to the additive component of the present invention or the additive component of the lubricating oil composition means the total base number (mg KOH/g) as measured by ASTM D2896;

“KV₁₀₀"means kinematic viscosity at 100 ℃ as measured by ASTM D445;

"phosphorus content" is measured by ASTM D5185;

"Sulfur content" is measured by ASTM D2622; and

"sulfated ash content" is measured by ASTM D874.

All percentages reported are mass% based on the active ingredient, i.e., without regard to the carrier or diluent oil, unless otherwise indicated.

In addition, it is to be understood that the various components used, necessary and best and conventional may react under the conditions of formulation, storage or use and that the invention also provides products obtainable or obtained as a result of any such reaction.

Further, it is understood that the upper and lower limits of any amount, range, and ratio described herein can be independently combined. Thus, any upper and lower limits of amounts, ranges and ratios recited herein with respect to a particular feature of the invention may be independently combined with any upper and lower limits of amounts, ranges and ratios recited herein with respect to one or more other particular features of the invention. Furthermore, any particular feature of the invention and all of its preferred variations may be combined independently with any other particular feature and all of its preferred variations.

It should also be understood that preferred features of each aspect of the invention are to be considered as preferred features of each of the other aspects of the invention.

Detailed Description

Features of the invention in respect of each and all aspects of the invention will now be described in more detail, if appropriate:

oil of lubricating viscosity (A)

An oil of lubricating viscosity (sometimes referred to as a "base stock" or "base oil") is the primary liquid component of the lubricant, into which additives, and possibly other oils, are blended, for example, to produce the final lubricant (or lubricant composition). The base oil is used to prepare the concentrate and to prepare the lubricating oil composition therefrom and may be selected from natural (vegetable, animal or mineral) and synthetic lubricating oils and mixtures thereof.

The group of base stocks is defined in the American Petroleum Institute (API) publication "Engine oil licensing and Certification System", Industrial Services Department, 14 th edition, month 12 1996, appendix 1, month 12 1998. Typically the base stock will have a particle size of preferably 3 to 12, more preferably 4 to 10, most preferably 4.5 to 8mm at 100 ℃²Viscosity per s (cSt).

The definition of base stocks and base oils in the present invention is the same as those found in the American Petroleum Institute (API) publication "Engine Oil Licensing and verification System", Industry Services Department, 14 th edition, 12.1996, appendix 1, 12.1998. The publication classifies base stocks as follows:

a) group I basestocks contain less than 90% saturates and/or greater than 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods described in Table E-1.

b) Group II basestocks contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods described in Table E-1.

c) Group III basestocks contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 120 using the test methods described in Table E-1.

d) Group IV basestocks are poly α olefins (PAO).

e) Group V basestocks include all other basestocks not included in group I, II, III or IV.

Table E-1: method for analyzing base oil

Performance of	Test method
		Saturates	ASTM D 2007
Viscosity index	ASTM D 2270
		Sulfur	ASTM D 2622
	ASTM D 4294
			ASTM D 4927
	ASTM D 3120

Other oils of lubricating viscosity that may be included in the lubricating oil composition are described in detail below:

natural oils include animal oils and vegetable oils (e.g., castor oil and lard oil); liquid petroleum oils and hydrorefined, solvent-treated mineral lubricating oils of the paraffinic, naphthenic and mixed paraffinic-naphthenic types. Oils of lubricating viscosity derived from coal or shale are also useful as base oils.

Synthetic lubricating oils include hydrocarbon oils such as polymerized and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene-isobutylene copolymers, chlorinated polybutylenes, poly (1-hexenes), poly (1-octenes), poly (1-decenes)); alkylbenzenes (e.g., dodecylbenzene, tetradecylbenzene, dinonylbenzene, di (2-ethylhexyl) benzene); polyphenols (e.g., biphenyls, terphenyls, alkylated polyphenols); and alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof.

Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic acids, alkenyl malonic acids) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol). Specific examples of these esters include dibutyl adipate, di (2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the mixed esters formed by reacting 1 mole of sebacic acid with 2 moles of tetraethylene glycol and 2 moles of 2-ethylhexanoic acid.

Esters useful as synthetic oils also include those made from C₅-C₁₂Monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol and tripentaerythritol.

Unrefined, refined and re-refined oils may be used in the compositions of the present invention. Unrefined oils are those obtained directly from a natural or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process and used without further treatment is an unrefined oil. Refined oils are similar to unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques, such as distillation, solvent extraction, acid or base extraction, filtration and diafiltration, are known to those skilled in the art. Rerefined oils are obtained by applying to already used refined oils processes similar to those used to obtain refined oils. Such rerefined oils are also known as reclaimed or reprocessed oils and are also typically processed by techniques for removing spent additives and oil breakdown products.

Other examples of base oils are gas to liquid ("GTL") base oils, i.e., the base oil may be an oil derived from Fischer-Tropsch synthesized hydrocarbons derived from a Fischer-Tropsch derived hydrocarbon containing H using a Fischer-Tropsch catalyst₂And CO synthesis gas production. These hydrocarbons typically require further processing to be used as base oils. For example, they may be hydroisomerized by methods known in the art; hydrocracking and hydroisomerization; dewaxing; or hydroisomerization and dewaxing.

While the composition of the base oil depends on the particular application of the lubricating oil composition and the oil formulator selects a base oil to achieve the desired performance characteristics at a reasonable cost, the base oil of the lubricating oil composition of the present invention typically comprises no more than 85 mass% group IV base oil, the base oil may comprise no more than 70 mass% group IV base oil, or even no more than 50 mass% group IV base oil. The base oil of the lubricating oil composition of the present invention may comprise 0 mass% of a group IV base oil. Alternatively, the base oil of the lubricating oil composition of the present invention may comprise at least 5 mass%, at least 10 mass% or at least 20 mass% of the group IV base oil. The base oil of the lubricating oil composition of the present invention may comprise from 0 to 85 mass%, or from 5 to 85 mass%, alternatively from 10 to 85 mass% of a group IV base oil.

Preferably, the oil or oil mixture of lubricating viscosity has a volatility of less than or equal to 20%, preferably less than or equal to 16%, preferably less than or equal to 12%, more preferably less than or equal to 10%, as measured by the NOACK test (ASTM D5800). Preferably, the oil of lubricating viscosity has a Viscosity Index (VI) of at least 95, preferably at least 110, more preferably up to 120, even more preferably at least 125, most preferably about 130-.

The oil of lubricating viscosity is provided in a major amount in combination with a minor amount of additive components (B) and (C) as defined herein, and if desired one or more co-additives as described hereinafter, to constitute a lubricating oil composition. The preparation can be achieved by adding the additives directly to the oil or by adding them in the form of their concentrates to disperse or dissolve the additives. The additives may be added to the oil before, simultaneously with, or after the addition of other additives by any method known to those skilled in the art.

Preferably, the oil of lubricating viscosity is present in an amount greater than 55 mass%, more preferably greater than 60 mass%, even more preferably greater than 65 mass%, based on the total mass of the lubricating oil composition. Preferably, the oil of lubricating viscosity is present in an amount of less than 98 mass%, more preferably less than 95 mass%, even more preferably less than 90 mass%, based on the total mass of the lubricating oil composition.

When the concentrates are used to prepare lubricating oil compositions, they may be diluted, for example, with from 3 to 100 parts by mass, for example from 5 to 40 parts by mass, of oil of lubricating viscosity per part by mass of concentrate.

Preferably, the lubricating oil composition is a multigrade oil (multigrade oil) identified by the viscometric descriptors SAE 20WX, SAE 15WX, SAE 10WX, SAE 5WX, or SAE 0WX, wherein X represents any one of 20, 30, 40, and 50; the characteristics of different viscometric grades can be found in the SAE J300 classification. In one embodiment of each aspect of the invention, and not dependent on the other embodiment, the lubricating oil composition is in the form of an SAE 10WX, an SAE 5WX, or an SAE 0WX, preferably an SAE 5WX or an SAE 0WX, wherein X represents any one of 20, 30, 40 and 50. Preferably, X is 20 or 30.

Polymeric Friction modifier (B)

The oil-soluble or oil-dispersible polymeric friction modifier (B) is the reaction product of only:

(i) a functionalized polyolefin as defined herein;

(ii) a polyalkylene glycol;

(iii) a polyol; and

(iv) polycarboxylic acids, as defined herein.

By the phrase "only", we mean that the oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in various aspects of the present invention is a copolymer derived from the reaction of only a functionalized polyolefin, a polyalkylene glycol, a polyol, and a polycarboxylic acid (i.e., a copolymer that is the reaction product of only the functionalized polyolefin(s), the polyalkylene glycol(s), the polyol(s), and the polycarboxylic acid (s)).

Functionalized polyolefin (B (i))

The one or more functionalized polyolefins are polyolefins comprising at least one diacid or anhydride functional group. The functionalized polyolefin or polyolefins are preferably derived from the polymerization of olefins having 2 to 6 carbon atoms, especially mono-olefins, such as ethylene, propylene, but-1-ene, and isobutylene (i.e., 2-methylpropene), and the resulting polyalkene is functionalized with diacid or anhydride functionality. Preferably, the one or more functionalized polyolefins are poly (C) functionalized with diacid or anhydride functionality₂-C₆An olefin). Even more preferably, the one or more functionalized polyolefins are derived from the polymerization of isobutylene and the resulting polyisobutylene is functionalized with diacid or anhydride functionality (i.e., the functionalized polyolefin is a functionalized polyisobutylene).

The polyolefin portion of the one or more functionalized polyolefins (e.g., poly (C)₂-C₆Olefins)) suitably contain a carbon chain of from 15 to 500 (e.g. 35 to 500, 40 to 500, 50 to 500), preferably 50 to 200 carbon atoms. Suitably, the one or more functional groupsThe polyolefin fraction of the functionalized polyalkene has a number average molecular weight (Mn) of 300-.

The functionalized polyolefin comprises at least one diacid or anhydride functional group capable of reacting with the hydroxyl functional groups of the polyalkylene glycol (B (ii)) or the hydroxyl functional groups of the polyol (B (iii)). Thus, functionalized polyolefins may be formed by reacting a polyalkene (i.e., a poly (olefin)) with an unsaturated diacid or anhydride. Preferably, the functionalized polyolefin comprises anhydride functional groups. Suitably, the anhydride functionalized polyolefin is derived from a polyolefin (e.g. poly (C)₂-C₆Olefins)) with anhydrides, especially maleic anhydride forming the succinic anhydride functionality. Thus, the functionalized polyolefin comprises anhydride functionality, in particular succinic anhydride functionality.

Thus, the preferred functionalized polyolefin or polyolefins are polyolefins containing anhydride functional groups, more preferably poly (C) containing anhydride functional groups₂-C₆Olefin), even more preferably a poly (C) comprising succinic anhydride functional groups₂-C₆Olefins), especially Polyisobutylene (PIB) -i.e., polyisobutylene succinic anhydride (PIBSA) -containing succinic anhydride functional groups. Suitably, the polyisobutylene of the PIBSA has a number average molecular weight (Mn) of 300-. PIB is a commercially available compound and is sold under the trade name Glissopal by BASF, and this product can be reacted to give the functionalized polyolefin (B (i)).

Suitably, the functionalized polyolefin comprising diacid or anhydride functionality as described herein (e.g., poly (C) comprising diacid or anhydride functionality₂-C₆Olefin), even more preferably a poly (C) comprising succinic anhydride functional groups₂-C₆Olefins), especially Polyisobutylene (PIB) containing succinic anhydride functionality, i.e., polyisobutylene succinic anhydride (PIBSA), via a suitable unsaturated diacid or anhydride, e.g., maleic anhydride, with a polyalkene, e.g., poly (C)₂-C₆Olefins), preferably Polyisobutylene (PIB)), by direct thermal condensation reactions (i.e., thermal ene reactions). This process is known as a thermal ene reaction and is typically carried out at a temperature of greater than 150 ℃ for 1 to 48 hours. The functionalized polyolefins formed by the thermal ene reaction are chemically unique and have properties comparable to those of the polyolefins formed by the chlorination process (i.e., poly-olefins)Chlorination of the alkene followed by reaction with a suitable diacid or anhydride) to form a comparative functionalized polyolefin having different physical and chemical properties.

Polyalkylene glycol (B (ii))

Suitably, the one or more polyalkylene glycols is poly (C)₂-C₂₀Alkylene) glycols, preferably poly (C)₂-C₁₀Alkylene) glycol, more preferably poly (C)₂-C₆Alkylene) glycols. Preferred polyalkylene glycol(s) are one or more polyethylene glycol(s) or one or more polypropylene glycol(s), or one or more mixed poly (ethylene-propylene) glycol(s), or combinations thereof. The most preferred polyalkylene glycol or glycols is one or more polyethylene glycols (PEGs), especially water-soluble PEGs.

The polyalkylene glycol comprises 2 hydroxyl groups capable of reacting with the functional groups of the functionalized polyolefin (b (i)) thereby forming a basic polyalkylene-polyalkylene glycol copolymer, and/or with a polycarboxylic acid (b (iv)) thereby forming a basic polyalkylene-polyalkylene glycol-carboxylic acid compound or a polyalkylene glycol-carboxylic acid compound. It is to be understood that such compounds may further react with functionalized polyolefins (b (i)), polyalkylene glycols (b (ii)), polyols (b (iii)) and/or polycarboxylic acids (b (iv)).

Suitably, the polyalkylene glycol (e.g. PEG) has a number average molecular weight (Mn) of 300-. Thus, in a preferred embodiment, the polyalkylene glycol (B) (ii) is PEG₄₀₀、PEG₆₀₀Or PEG₁₀₀₀. Suitably, PEG₄₀₀、PEG₆₀₀And PEG₁₀₀₀Commercially available from Croda International.

Polyol (B (iii))

The polyol reactant is capable of reacting with the functionalized polyolefin, thereby providing backbone moieties that together link separate functionalized polyolefin blocks. Suitably, when the functionalized polyalkene is functionalized with anhydride or diacid functionality, the polyol provides the backbone moiety that is linked together via ester linkages to separate polyalkene blocks.

Suitably, the polyol reactant is also capable of reacting with a polycarboxylic acid, thereby providing a polyol-carboxylic acid compound, wherein the compound may be further reacted with the functionalized polyolefin (b (i)) and/or the polyalkylene glycol (b (ii)).

The polyol is an alcohol (i.e., a polyol) containing 2 or more hydroxyl functional groups, but does not include the "polyalkylene glycol" (component b (ii)) used to form the oil-soluble or oil-dispersible polymeric friction modifier. Preferably, the polyol contains 3 or more hydroxyl functional groups. Thus, the polyol may be a diol, triol, tetraol (tetrol), and/or related dimer or chain extended polymers of such compounds. Suitably, the one or more polyols are C₂-C₂₀Hydrocarbyl polyol, more preferably C₂-C₂₀Aliphatic hydrocarbyl polyols, even more preferably saturated C₂-C₂₀Aliphatic hydrocarbyl polyols, even more preferably saturated C₂-C₁₅An aliphatic hydrocarbyl polyol. Suitably, the polyol has a molecular weight (Mw) of less than or equal to 400 daltons, preferably less than or equal to 350 daltons, more preferably less than or equal to 300 daltons, most preferably less than or equal to 280 daltons. Examples of suitable polyols include glycerol, neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol. A highly preferred polyol is glycerol.

Polycarboxylic acid (B (iv))

The polycarboxylic acid reactant is capable of reacting with the hydroxyl groups of the polyalkylene glycol (b (ii)), thereby providing a backbone moiety that is linked together by ester linkages to separate polyalkylene glycol blocks.

Suitably, the polycarboxylic acid is also capable of reacting with a polyol (b (iii)), thereby providing a polyol-carboxylic acid compound, wherein the compound may be further reacted with a functionalised polyolefin (b (i)) and/or a polyalkylene glycol (b (ii)).

Polycarboxylic acids are organic acids having 2 or more carboxylic acid groups. The polycarboxylic acids may be di-, tri-and tetra-carboxylic acids; dicarboxylic acids are preferred. Suitably, the one or more polycarboxylic acids is C₂-C₃₀Hydrocarbon polycarboxylic acids, preferably C₂-C₂₀Hydrocarbon polycarboxylic acids, even more preferablyC₂-C₃₀Hydrocarbyl dicarboxylic acids, even more preferably C₂-C₂₀Hydrocarbyl dicarboxylic acids, even more preferably C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid. Still even more preferably, the one or more polycarboxylic acids is acyclic C₂-C₃₀Aliphatic hydrocarbyl dicarboxylic acids, even more preferably acyclic C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid. Linear polycarboxylic acids are preferred over branched chain polycarboxylic acids. Saturated polycarboxylic acids are preferred over unsaturated polycarboxylic acids, such as maleic acid.

Thus, the one or more preferred polycarboxylic acids is C₂-C₃₀Hydrocarbon polycarboxylic acids, e.g. saturated C₂-C₃₀Hydrocarbon polycarboxylic acids (e.g. saturated C)₂-C₃₀Hydrocarbyl dicarboxylic acid), more preferably C₂-C₃₀Aliphatic hydrocarbyl polycarboxylic acids, e.g. saturated C₂-C₃₀Aliphatic hydrocarbyl polycarboxylic acids (e.g. saturated C)₂-C₃₀Aliphatic hydrocarbyl dicarboxylic acids), more preferably C₂-C₂₀Aliphatic hydrocarbyl polycarboxylic acids, e.g. saturated C₂-C₂₀Aliphatic hydrocarbyl polycarboxylic acids (e.g. saturated C)₂-C₂₀Aliphatic hydrocarbyl dicarboxylic acids), even more preferably C₆-C₂₀Aliphatic hydrocarbyl polycarboxylic acids, e.g. saturated C₆-C₂₀Aliphatic hydrocarbyl polycarboxylic acids (e.g. saturated C)₆-C₂₀Aliphatic hydrocarbyl dicarboxylic acids), even more preferably C₈-C₂₀Aliphatic hydrocarbyl polycarboxylic acids, e.g. saturated C₈-C₂₀Aliphatic hydrocarbyl polycarboxylic acids (e.g. saturated C)₈-C₂₀Aliphatic hydrocarbyl dicarboxylic acids — especially sebacic acid).

Suitable polycarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid. The most preferred polycarboxylic acid is sebacic acid.

Thus, according to a very preferred embodiment, the oil-soluble or oil-dispersible polymeric friction modifier (B) is the reaction product of only:

(i) PIBSA as defined herein;

(ii) polyethylene glycol as defined herein;

(iii) a polyol, preferably glycerol; and

(iv) polycarboxylic acids, preferably sebacic acid.

Suitably, during the formation of the polymeric friction modifier, various reactions between the functionalized polyolefin (b (i)), the polyalkylene glycol (b (ii)), the polyol (b (iii)), and the polycarboxylic acid (b (iv)) may occur. For example, the functionalized polyolefin and polyalkylene glycol may be reacted such that the polyolefin is directly attached to the polyalkylene glycol (e.g., via an ester linkage), and subsequent reaction may occur between the resulting polymer and the functionalized polyolefin, polyalkylene glycol, polyol, and/or polycarboxylic acid. Alternatively or additionally, the polyalkylene glycol may be reacted with a polycarboxylic acid to form polyalkylene glycol blocks linked together by esterified polycarboxylic acids, and subsequent reactions may take place between the resulting polyalkylene glycol and the functionalized polyolefin and/or functionalized polyolefin blocks. Still further, the functionalized polyolefin may be reacted with a polyol to form functionalized polyolefin blocks linked together (typically via ester linkages) by the polyol, and subsequent reactions may occur between the resulting functionalized polyolefin blocks and polyalkylene glycol and/or polyalkylene glycol blocks.

Thus, the functionalized polyolefin, polyalkylene glycol, polyol, and polycarboxylic acid may react to form a block copolymer. When present, the number of block copolymer units in the organic friction modifier additive is generally from 2 to 20, preferably from 2 to 15, more preferably from 2 to 10 units.

Like all polymers, polymeric friction modifiers generally comprise a mixture of molecules having various sizes. The polymeric friction modifier (B) suitably has a number average molecular weight of 1,000-30,000 daltons, preferably 1,500-25,000 daltons, more preferably 2,000-20,000 daltons.

The polymeric friction modifier (B) suitably has an acid number of less than 20, preferably less than 15, more preferably less than 10mg KOH/g (ASTM D974). The polymeric friction modifier (B) suitably has an acid number of greater than 1, preferably greater than 1.5mg KOH/g. In a preferred embodiment, the polymeric friction modifier (B) has an acid number of from 1.5 to 9.

The polymeric friction modifier (B) may be prepared by techniques well known to those skilled in the art, for example, as described in U.S. patent application No.13/582,589. Typically, the functionalized polyalkene, polyalkylene glycol, polyol and polycarboxylic acid are heated and water is removed in the presence of a catalyst (e.g., tetrabutyl titanate) at 100 ℃ and 250 ℃.

In a preferred embodiment, the polymeric friction modifier (B) is a reaction product of maleated Polyisobutylene (PIBSA), PEG, glycerol, and sebacic acid, wherein the polyisobutylene of maleated Polyisobutylene (PIBSA) has a number average molecular weight of about 950 daltons, the PIBSA has an approximate saponification value of 98mg KOH/g, and the PEG has a number average molecular weight of about 600 daltons and a hydroxyl value of 190mg KOH/g. Suitable additives can be prepared by mixing 158.4g (0.128 mole) PIBSA, 101g (0.168 mole) PEG₆₀₀10.4g (0.0514 moles) sebacic acid and 7.7g (0.0835 moles) glycerol were charged to a glass round bottom flask equipped with nitrogen purge, mechanical stirrer, Isomantle heater and distillation arm. The reaction was carried out in the presence of 0.5ml of tetrabutyltitanate as esterification catalyst at 230 ℃ at 180 ℃ with removal of water to a final acid number of 1.7 mg/KOH/g. Thus, the optional polymeric friction modifier (B) may be prepared by a similar synthetic method.

The polymeric friction modifier (B) is suitably present in the lubricating oil composition of the present invention in an amount of at least 0.1 mass%, preferably at least 0.2 mass%, based on the total mass of the lubricating oil composition, on an active material basis. The polymeric friction modifiers of the present invention are suitably present in the lubricating oil composition in an amount of less than or equal to 5 mass%, preferably less than or equal to 3 mass%, more preferably less than or equal to 1.5 mass%, based on the total mass of the lubricating oil composition, on an active material basis.

Dihydrocarbyl dithiophosphate Metal salt (C)

For the lubricating oil compositions of the present invention, any suitable oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate metal salt having antiwear properties may be used in the lubricating oil composition. Of note are dihydrocarbyl dithiophosphate metal salts wherein the metal may be an alkali or alkaline earth metal, or aluminum, lead, tin, molybdenum, manganese, nickel, copper, or preferably zinc. Thus, the preferred metal dihydrocarbyl dithiophosphates are dihydrocarbyl dithioZinc phosphate (ZDDP), more preferably zinc dialkyldithiophosphate, especially di (C)₂-C₈Zinc alkyl) dithiophosphate of which di (C)₂-C₈Alkyl) zinc dithiophosphate C₂-C₈The alkyl groups may be the same or different.

Dihydrocarbyl dithiophosphate metal salts may be prepared according to known techniques as follows: first, usually by reacting one or more alcohols or phenols with P₂S₅Reacting to form a dihydrocarbyl dithiophosphoric acid (DDPA), and then neutralizing the formed DDPA with a metal compound. For example, dithiophosphoric acids can be prepared by reacting mixtures of primary and secondary alcohols. Alternatively, a variety of dithiophosphoric acids may be prepared wherein the hydrocarbyl groups on one are completely secondary in nature and the hydrocarbyl groups on the other are completely primary in nature. To prepare the metal salt, any basic or neutral metal compound may be used, but oxides, hydroxides and carbonates are most commonly used. Commercial additives typically contain an excess of metal due to the use of an excess of basic metal compound in the neutralization reaction.

Preferred Zinc Dihydrocarbyl Dithiophosphates (ZDDP) are oil soluble salts of dihydrocarbyl dithiophosphoric acids and may be represented by the formula:

wherein R and R' may be the same or different hydrocarbyl groups containing from 1 to 18, preferably from 2 to 12, carbon atoms including groups such as alkyl, alkenyl, aryl, aralkyl, alkaryl and cycloaliphatic groups. Particular preference is given to alkyl groups having from 2 to 8 carbon atoms as radicals R and R'. Thus, the radicals may be, for example, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, pentyl, n-hexyl, isohexyl, n-octyl, decyl, dodecyl, octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl, methylcyclopentyl, propenyl, butenyl. To obtain oil solubility, the total number of carbon atoms (i.e., R and R') in the dithiophosphoric acid will generally be about 5 or greater. Thus, the zinc dihydrocarbyl dithiophosphate may comprise zinc dialkyl dithiophosphates.

Dihydrocarbyl dithiophosphate metal salts, such as ZDDP, are added to lubricating oil compositions in amounts sufficient to provide the lubricating oil with no more than 1200 mass ppm, preferably no more than 1000 mass ppm, more preferably no more than 900 mass ppm, and most preferably no more than 850 mass ppm phosphorus, based on the total mass of the lubricating oil composition and as determined in accordance with ASTM D5185. The dihydrocarbyl dithiophosphate metal salt, e.g., ZDDP, is suitably added to the lubricating oil composition in an amount sufficient to provide the lubricating oil with at least 100 ppm, preferably at least 350 ppm, more preferably at least 500ppm, by mass phosphorus, based on the total mass of the lubricating oil composition and as determined in accordance with astm d 5185.

Suitably, the dihydrocarbyl dithiophosphate metal salt, e.g., ZDDP, is present in an amount of greater than or equal to 0.1 mass%, preferably greater than or equal to 0.25 mass%, more preferably greater than or equal to 0.5 mass%, based on the total mass of the lubricating oil composition. Suitably, the dihydrocarbyl dithiophosphate metal salt, e.g., ZDDP, is present in an amount less than or equal to 10 mass%, preferably less than or equal to 5.0 mass%, more preferably less than or equal to 3.0 mass%, based on the total mass of the lubricating oil composition.

Engine

The lubricating oil compositions of the present invention may be used to lubricate mechanical engine components, particularly internal combustion engines, for example spark-ignited or compression-ignited internal combustion engines, particularly spark-ignited or compression-ignited 2-stroke or 4-stroke reciprocating engines, by adding the composition thereto. The engine may be a conventional gasoline or diesel engine designed to be powered by gasoline or petroleum diesel, respectively; alternatively, the engine may be specifically modified to be powered by an alcohol-based fuel or a biodiesel fuel.

Additive aid

Co-additives other than additive components (B) and (C) may also be present with typical effective amounts as set forth below. All listed values are described as mass% active in fully formulated lubricants.

Additive agent	(Wide)	(preferred) in mass%)
			Ashless dispersants	0.1-20	1-8
Metal detergent	0.1-15	0.2-9
			Friction modifiers	0-5	0-1.5
Corrosion inhibitors	0-5	0-1.5
			Metal dihydrocarbyl dithiophosphates	0-10	0-4
Antioxidant agent	0-5	0.01-3
			Pour point depressant	0.01-5	0.01-1.5
Defoaming agent	0-5	0.001-0.15
			Supplemental antiwear agent	0-5	0-2
Viscosity improver (1)	0-10	0.01-4
			Mineral or synthetic base oils	Balance of	Balance of

(1) Viscosity modifiers are used only in multigrade oils.

The final lubricating oil composition, which is typically prepared by blending the or each additive into a base oil, may comprise from 5 to 25 mass%, preferably from 5 to 18 mass%, typically from 7 to 15 mass%, of the co-additive, the remainder being oil of lubricating viscosity.

Suitably, the lubricating oil composition comprises a minor amount of one or more co-additives other than additive components (B) and (C), selected from ashless dispersants, metal detergents, corrosion inhibitors, antioxidants, pour point depressants, antiwear agents, friction modifiers, demulsifiers, antifoamants and viscosity modifiers.

The above-mentioned co-additives are discussed in further detail below; as is known in the art, some additives may provide a multiplicity of effects, e.g., a single additive may act as both a dispersant and an oxidation inhibitor.

Metal detergentAct as detergents to reduce or remove deposits and act as acid neutralizers or rust inhibitors, thereby reducing wear and corrosion and extending engine life. Detergents generally comprise a polar head with a long hydrophobic tail, the polar head comprising a metal salt of an acidic organic compound. In the case where they are generally described as normal or neutral salts, the saltsThe metal may be included in substantially stoichiometric amounts and typically has a total base number or TBN (as can be measured by ASTM D2896) of from 0 to 80mg KOH/g. Large amounts of metal base (metal base) can be incorporated by reacting an excess of metal compound (e.g., oxide or hydroxide) with an acidic gas (e.g., carbon dioxide). The resulting overbased detergent comprises neutralized detergent as the outer layer of a metal base (e.g., carbonate) micelle. Such overbased detergents may have a TBN of 150mg KOH/g or greater, and typically have a TBN of 250-450mg KOH/g or greater. In the presence of the compound of formula I, the amount of overbased detergent may be reduced, or detergents having a reduced level of overbased (e.g., detergents having a TBN of 100-200mg KOH/g) or neutral detergents may be used, resulting in a corresponding reduction in the SASH content of the lubricating oil composition without a reduction in its performance.

Detergents which may be used include oil-soluble neutral and overbased sulfonates, phenates, sulfurized phenates, thiophosphonates, salicylates, and naphthenates of metals, particularly alkali or alkaline earth metals such as sodium, potassium, lithium, calcium, and magnesium, as well as other oil-soluble carboxylates. The most commonly used metals are calcium and magnesium, which may all be present in detergents used in lubricants, and mixtures of calcium and/or magnesium with sodium. Combinations of detergents, whether overbased or neutral or both, may be used.

In one embodiment of the invention, the lubricating oil composition comprises a metal detergent selected from the group consisting of neutral or overbased calcium sulfonates having a TBN of from 20 to 450mg KOH/g, and neutral and overbased calcium phenates and sulfurized phenates having a TBN of from 50 to 450mg KOH/g, and mixtures thereof.

Sulfonates can be prepared from sulfonic acids, which are typically obtained by sulfonation of alkyl-substituted aromatic hydrocarbons such as those obtained from petroleum fractionation or by alkylation of aromatic hydrocarbons. Examples include those obtained by alkylating benzene, toluene, xylene, naphthalene, biphenyl or halogen derivatives thereof such as chlorobenzene, chlorotoluene and chloronaphthalene. The alkylation may be carried out with an alkylating agent having from about 3 to more than 70 carbon atoms in the presence of a catalyst. The alkylaryl sulfonates typically contain from about 9 to about 80 or more carbon atoms, preferably from about 16 to about 60 carbon atoms per alkyl-substituted aromatic moiety. The oil soluble sulfonates or alkaryl sulfonic acids may be neutralized with oxides, hydroxides, alkoxides, carbonates, carboxylates, sulfides, hydrosulfides, nitrates, borates and ethers of the metal. The amount of metal compound is selected with respect to the TBN of the desired end product, but is typically about 100-220 mass% (preferably at least 125 mass%) of the stoichiometrically desired.

The metal salts of phenols and sulfurized phenols are prepared by reaction with a suitable metal compound such as an oxide or hydroxide, and neutral or overbased products may be obtained by methods well known in the art. Sulfurized phenols can be prepared by reacting a phenol with sulfur or a sulfur-containing compound such as hydrogen sulfide, sulfur monohalide or sulfur dihalide to form a mixture which is typically a compound in which 2 or more phenols are bridged by a sulfur-containing bridge.

In another embodiment of the invention, the lubricating oil composition comprises a metal detergent which is a neutral or overbased alkali or alkaline earth metal salicylate having a TBN of 50 to 450mg KOH/g, preferably 50 to 250mg KOH/g, or a mixture thereof. Highly preferred salicylate detergents include alkaline earth metal salicylates, particularly magnesium and calcium, especially calcium salicylate. In one embodiment of the invention, the alkali or alkaline earth metal salicylate detergent is the only metal-containing detergent in the lubricating oil composition.

Supplements other than dihydrocarbyl dithiophosphate metal salts (additive component (C)) that may be included in lubricating oil compositionsAntiwear agentIncluding 1,2, 3-triazole, benzotriazole, sulfurized fatty acid esters, and dithiocarbamate derivatives.

Ashless dispersantsComprising an oil-soluble polymeric hydrocarbon backbone having functional groups capable of associating with the particles to be dispersed. Typically, the dispersants comprise amine, alcohol, amide or ester polar moieties attached to the polymer backbone, typically via a bridging group. The ashless dispersant may be selected, for example, from oil-soluble salts, esters, aminoesters, amides, imides and anhydrides of long chain hydrocarbon-substituted mono-and dicarboxylic acids or anhydrides thereof

An oxazoline; thiocarboxylate derivatives of long chain hydrocarbons; long chain aliphatic hydrocarbons having a polyamine attached directly thereto; and Mannich condensation products formed by condensing a long chain substituted phenol with formaldehyde and a polyalkylene polyamine.

Friction modifiersMonoglycerides including higher fatty acids, such as Glycerol Monooleate (GMO); esters of long chain polycarboxylic acids with diols, such as the butanediol ester of dimerized unsaturated fatty acids;

an oxazoline compound; and alkoxylated alkyl-substituted mono-amines, diamines and alkyl ether amines, such as ethoxylated tallow amines and ethoxylated tallow ether amines.

Generally, the total amount of other organic ashless friction modifiers in the lubricants of the present invention is not more than 5 mass%, preferably not more than 2 mass%, more preferably not more than 0.5 mass%, based on the total mass of the lubricating oil composition. In one embodiment of the invention, the lubricating oil composition does not contain other organic ashless friction modifiers.

Other known friction modifiers include oil-soluble organo-molybdenum compounds. Such organo-molybdenum friction modifiers also provide antioxidant and antiwear benefits to the lubricating oil composition. Suitable oil-soluble organo-molybdenum compounds have a molybdenum-sulfur core. As examples, mention may be made of dithiocarbamates, dithiophosphates, dithiophosphinates, xanthates, thioxanthates, sulfides, and the like, and mixtures thereof. Molybdenum dithiocarbamates, dialkyldithiophosphates, alkylxanthates and alkylthioxanthates are particularly preferred. The molybdenum compound is dinuclear or trinuclear.

A preferred class of organomolybdenum compounds for use in all aspects of the invention is that of the formula Mo₃S_kL_nQ_zWherein L is independently selected from ligands containing organic groups having a sufficient number of carbon atoms to render the compound soluble or dispersible in oil, n is from 1 to 4, k is from 4 to 7, Q is selected from neutral electron donor compounds such as water, amines, alcohols, phosphines, and ethers, and z ranges from 0 to 5 and includes non-stoichiometric values. At the placeAt least 21 total carbon atoms should be present in the organic group with the ligand, for example at least 25, at least 30 or at least 35 carbon atoms.

The molybdenum compound may be present in the lubricating oil composition at a concentration of 0.1 to 2 mass%, or to provide at least 10 mass ppm, for example 50 to 2,000 mass ppm, of molybdenum atoms.

Preferably, the molybdenum from the molybdenum compound is present in an amount of from 10 to 1500ppm, for example from 20 to 1000ppm, more preferably from 30 to 750ppm, based on the total weight of the lubricating oil composition. For some applications, molybdenum is present in an amount greater than 500 ppm.

Viscosity improverSuitable viscosity modifiers are polyisobutylene, copolymers of ethylene and propylene and higher α -olefins, polymethacrylates, polyalkylmethacrylates, methacrylate copolymers, copolymers of unsaturated dicarboxylic acids and vinyl compounds, interpolymers of styrene and acrylates, and partially hydrogenated copolymers of styrene/isoprene, styrene/butadiene, and isoprene/butadiene, as well as partially hydrogenated homopolymers of butadiene and isoprene/divinylbenzene.

Sometimes referred to as oxidation inhibitorsAntioxidant agentThe resistance of the composition to oxidation is increased and it may be acted on by combining with and modifying the peroxides to render them harmless, by decomposing the peroxides, or by rendering the oxidation catalyst inert. Oxidative deterioration can be evidenced by sludge in the lubricant, varnish-like deposits on the metal surfaces, and by viscosity increase.

Examples of suitable antioxidants are selected from the group consisting of copper-containing antioxidants, sulfur-containing antioxidants, aromatic amine-containing antioxidants, hindered phenol antioxidants, dithiophosphate derivatives, and metal dithiocarbamates. Preferred antioxidants are aromatic amine-containing antioxidants, hindered phenol antioxidants and mixtures thereof. In a preferred embodiment, an antioxidant is present in the lubricating oil composition of the present invention.

Selected from nonionic polyoxyalkylene polyols and esters thereof, polyoxyalkylene phenols and anionic alkyl sulfonic acids may be usedRust inhibitor Preparation。

Can be usedCorrosion inhibitors with copper and leadHowever, this is not generally required for the formulations of the present invention. Typically, such compounds are thiadiazole polysulfides containing from 5 to 50 carbon atoms, their derivatives and polymers thereof. Derivatives of 1,3,4 thiadiazole such as those described in U.S. patent nos.2,719,125; 2,719,126, respectively; and 3,087,932 are typical. Other similar materials are described in U.S. patent nos.3,821,236; 3,904,537, respectively; 4,097,387; 4,107,059, respectively; 4,136,043, respectively; 4,188,299, respectively; and 4,193,882. Other additives are thio and polysulfur sulfonamides of thiadiazoles (polythiosulfenamides), such as those described in british patent specification No.1,560,830. Benzotriazole derivatives also belong to this class of additives. When these compounds are included in the lubricating composition, they are preferably present in an amount not exceeding 0.2 wt% active ingredient.

Can be used in small amountDemulsifying component. Preferred demulsifying components are described in EP 330522. It is obtained by reacting an alkylene oxide with an adduct obtained by reacting a diepoxide with a polyol. The demulsifier should be used at a level not exceeding 0.1 mass% of the active ingredient. A treat rate of 0.001-0.05 mass% active ingredient is convenient.

Otherwise known as lubricating oil flow improversPour point depressantReducing the minimum temperature at which the fluid will flow or can be poured. Such additives are well known. Typical of those additives which improve the low temperature fluidity of the fluid is fumaric acid C₈-C₁₈Dialkyl ester/vinyl acetate copolymers, polyalkylmethacrylates, and the like.

Foam control can be provided by a number of compounds, including of the polysiloxane typeDefoaming agentFor example silicone oil or polydimethylsiloxane.

The additives may be incorporated into the base stock in any convenient manner. Thus, each component can be added directly to the base stock or base oil blend by dispersing or dissolving it in the base stock or base oil blend at the desired concentration level. The mixing can be carried out at ambient temperature or at elevated temperature.

Preferably, all of the additives, except the viscosity modifier and pour point depressant, are blended as an additive package into the concentrate or additive package described herein, which is then blended into the basestock to make the final lubricant. The concentrate is typically formulated to contain suitable amounts of additives to provide the desired concentration in the final formulation when the concentrate is combined with a predetermined amount of base lubricant.

The concentrate is preferably prepared according to the method described in US 4,938,880. This patent describes the preparation of a premix of an ashless dispersant and a metal detergent premixed at a temperature of at least about 100 ℃. Thereafter, the premix is cooled to at least 85 ℃ and the other components are added.

Typically, the additive package used to formulate the lubricating oil compositions of the present invention has a Total Base Number (TBN) as measured by ASTM D2896 of from 25 to 100, preferably from 45 to 80, and the lubricating oil compositions of the present invention have a Total Base Number (TBN) as measured by ASTM D2896 of from 4 to 15, preferably from 5 to 12. In one embodiment of the invention, the additive package does not have a Total Base Number (TBN) as measured by ASTM D2896 of from 62 to 63.5, and the lubricating oil composition does not have a Total Base Number (TBN) as measured by ASTM D2896 of from 9.05 to 9.27.

The final crankcase lubricating oil formulation may employ from 2 to 20 mass%, preferably from 4 to 18 mass%, most preferably from 5 to 17 mass% of the concentrate or additive package, with the remainder being basestock.

In one embodiment of the present invention, the lubricating oil composition according to the first aspect of the present invention does not comprise from 0.2 to 0.25 mass% sulphur, measured according to ASTM method D4927.

In one embodiment of the present invention, the lubricating oil composition according to the first aspect of the present invention does not contain 0.08 to 0.11 mass% nitrogen as measured according to ASTM method D5291.

Examples

The invention is now described in the following examples, which are not intended to limit the scope of the claims hereof.

Unless otherwise indicated, all additives described in the examples are available as standard additives from lubricant additives companies such as Infineum UK Ltd, Lubrizol Corporation and Afton Chemical Corporation.

Example 1 preparation of polymeric Friction modifier (B)

500cm of a distillation arm equipped with a nitrogen purge, a stirrer with a gas-tight stirrer bearing, a temperature probe and a connection to an outlet bubbler³A5-necked round bottom flask was charged with PIBSA (158.4g, 0.128 mole), PEG₆₀₀(101.0g, 0.168 moles), sebacic acid (10.4g, 0.0514 moles) and glycerol (7.7g, 0.0835 moles) and the mixture was heated at 180 ℃ with stirring for 1 hour. The reaction mixture was then heated to a temperature of 230 ℃ for 1 hour, and tetrabutyl titanate (0.5ml) was then added thereto and heating and stirring were continued at a temperature of 230 ℃ and a reduced pressure of 50 to 150 mbar for 2 hours. The reaction mixture was cooled to below 100 ℃ and the polymeric friction modifier (B) was poured from the round bottom flask. The polymeric friction modifier (B) had an acid value of 1.7mg KOH/g.

Example 2 Corrosion resistance

Six lubricating oil compositions (designated base lubricants and oils 1-5) were prepared. The base lubricant and oils 1-5 each contain the same group II base stock and the same amounts of the following same additives: an overbased calcium sulfonate detergent (TBN 300 mgKOH/g); a dispersant; an antioxidant; a molybdenum friction modifier; and a viscosity modifier. Oils 1-5 also contained other additives based on active ingredients as detailed in table 1. Those oils that contain ZDDP (i.e., oils 3-5) have a phosphorus content of 880ppm as measured by ASTM D5185. Oil 5 represents a lubricating oil composition of the present invention.

TABLE 1

¹The polymeric Friction modifier was the Compound of example 1

Test and results

Corrosion control was measured according to ASTM D6594-06 using the High Temperature Corrosion Bench Test (HTCBT). This test method simulates corrosion of nonferrous metals in lubricants (such as copper and lead found in cam followers and bearings); the corrosion processes studied are caused by lubricant chemistry rather than lubricant degradation or contamination.

Four metal coupons of copper, lead, tin and phosphor copper were immersed in a measured amount of test lubricant (100ml) in a test tube. The test tube was immersed in a hot oil bath so that the temperature of the test oil was heated to 135 ℃. The test oil was heated at 135 ℃ for 168 hours, during which time dry air was blown through the hot oil at a rate of 5 liters/hour. Thereafter, the test lubricant was cooled, and the metal specimen was taken out and examined for corrosion. The concentrations of copper, tin and lead in the test lubricating oil compositions and the reference lubricating oil composition samples (i.e., the new test lubricating oil samples) were then determined according to ASTM D5185. The difference between the concentrations of the various metal contaminants in the test lubricating oil compositions and those of the reference sample lubricating oil compositions provides the values for the variation in the concentrations of the various metals before and after the test. The industry standard limits for meeting API CJ-4 requirements are 20ppm maximum for copper and 120ppm maximum for lead. The results for the base lubricants and oils 1-5 are described in table 2.

TABLE 2

Etching of	Base lubricant	Oil 1	Oil 2	Oil 3	Oil 4	Oil 5
							Lead (ppm)	23	13	403	63	420	108
Copper (ppm)	33	29	49	27	22	9

As can be seen from the results in Table 2, the base lubricant containing no ZDDP, ashless organic friction modifier or polymeric friction modifier (B) produced 23ppm lead corrosion and 33ppm copper corrosion. Comparison of the results for oil 1, which corresponds to the base lubricant containing the polymeric friction modifier (B), with those of the base lubricant demonstrates that the inclusion of the polymeric friction modifier (B) in oil 1 inhibits corrosion of copper (29ppm relative to 33ppm) and lead (13ppm relative to 23 ppm). In contrast, the inclusion of an ashless organic friction modifier (GMO) (oil 2) in the base lubricant significantly enhanced lead (403ppm vs. 23ppm) and copper (49ppm vs. 33ppm) corrosion.

As can be seen from a comparison of the results for oil 3 with those of the base lubricant, the inclusion of ZDDP in the base lubricant increased lead corrosion (63ppm versus 23ppm), but showed marginal improvement in copper corrosion (27ppm versus 33 ppm). As can be seen from a comparison of the results for oil 4 with those of the base lubricant, the inclusion of ZDDP and ashless organic friction modifier (GMO) in the base lubricant (oil 4) significantly increased lead corrosion (420ppm versus 23ppm), but provided an improvement in copper corrosion (22ppm versus 33 ppm). From a comparison of the results for oil 5 (inventive lubricant comprising ZDDP and polymeric friction modifier (B)) with those for oil 4, it can be noted that the polymeric friction modifier (B) provided significantly less lead corrosion (108ppm versus 420ppm) than the ashless organic friction modifier present in oil 4, and that the polymeric friction modifier was far superior to the ashless organic friction modifier in inhibiting copper corrosion (9ppm versus 22 ppm). Furthermore, comparison of the results for oil 5 with those of the base lubricant clearly demonstrates that the presence of ZDDP and polymeric friction modifier provides a significant reduction in copper corrosion (9ppm versus 33 ppm).

Claims

1. A lubricating oil composition having a sulfated ash content of less than or equal to 1.2 mass% as determined by ASTM D874 and a phosphorus content of less than or equal to 0.12 mass% as determined by ASTM D5185, the lubricating oil composition comprising or prepared by admixing:

(A) a major amount of an oil of lubricating viscosity;

(B) an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier as an additive of at least 0.1 mass%, based on the total mass of the lubricating oil composition, which is the reaction product of only:

(

) One or more functionalized polyolefins which are poly (olefins) functionalized with at least one diacid or anhydride functional group, and wherein the poly (olefins) of the functionalized polyolefins have a carbon chain length of 50 to 500 carbon atoms;

(

) One or more polyalkylene glycols;

(

) One or more C₂-C₂₀An aliphatic hydrocarbyl polyol; and

(

) One or more polycarboxylic acids which are C₂-C₃₀A hydrocarbyl polycarboxylic acid;

and

(C) an effective minor amount of at least one oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is provided as an additive to a lubricating oil composition of at least 100 ppm by mass of phosphorus based on the total mass of the lubricating oil composition.

2. The composition according to claim 1, wherein the one or more functionalized polyolefins are poly (C) functionalized with at least one diacid or anhydride functional group₂-C₆Olefins) and functionalized polyolefins₂-C₆Olefin) moiety has a carbon chain length of 50 to 500 carbon atoms.

3. The composition according to claim 1, wherein the one or more functionalized polyolefins (B), (B: (B))

) ) is a polyisobutylene functionalized with at least one diacid or anhydride functional group.

4. The composition according to claim 2, wherein the one or more functionalized polyolefins (B), (B: (B))

5. The composition according to any of the preceding claims 1 to 4, wherein the one or more functionalized polyolefins (B: (B)) (

) Functionalized with succinic anhydride functionality).

6. The composition according to claim 1, wherein the one or more functionalized polyolefins (B), (B: (B))

) Is prepared fromPolyisobutylene succinic anhydride.

7. The composition according to any one of claims 1-4 or 6, wherein the one or more polyalkylene glycols (B: (B)) (

) Is poly (C)₂-C₆Alkylene) glycols.

8. The composition according to claim 5, wherein the one or more polyalkylene glycols (B), (B) and (C)

) Is poly (C)₂-C₆Alkylene) glycols.

9. The composition according to claim 7, wherein the one or more polyalkylene glycols is polyethylene glycol.

10. The composition according to claim 8, wherein the one or more polyalkylene glycols is polyethylene glycol.

11. The composition according to any of the preceding claims 1-4 or 6 or 8-10, wherein the one or more C s₂-C₂₀Aliphatic hydrocarbyl polyol (B: (B) ((B)

) Is selected from the group consisting of glycerol, neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, dipentaerythritol, tripentaerythritol, and sorbitol.

12. The composition according to claim 5, wherein the one or more C' s₂-C₂₀Aliphatic hydrocarbyl polyol (B: (B) ((B)

) Is selected from glycerol, neopentyl glycol,Trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, dipentaerythritol, tripentaerythritol and sorbitol.

13. The composition according to claim 7, wherein the one or more C' s₂-C₂₀Aliphatic hydrocarbyl polyol (B: (B) ((B)

14. The composition according to claim 11, wherein the one or more C' s₂-C₂₀The aliphatic hydrocarbyl polyol is glycerol.

15. The composition according to any one of claims 12-13, wherein the one or more C' s₂-C₂₀The aliphatic hydrocarbyl polyol is glycerol.

16. The composition according to any of the preceding claims 1-4 or 6 or 8-10 or 12-14, wherein the one or more polycarboxylic acids (B: (r))

) Is saturated C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid.

17. The composition according to claim 5, wherein the one or more polycarboxylic acids (B), (B

) Is saturated C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid.

18. The composition according to claim 7, wherein the one or more polycarboxylic acids (B), (B

) Is saturated C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid.

19. The composition according to claim 11, wherein the one or more polycarboxylic acids (B), (B

) Is saturated C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid.

20. The composition according to claim 15, wherein the one or more polycarboxylic acids (B), (B

) Is saturated C₂-C₂₀An aliphatic hydrocarbyl dicarboxylic acid.

21. The composition according to claim 16, wherein the one or more saturated C' s₂-C₂₀The aliphatic hydrocarbyl dicarboxylic acid is sebacic acid.

22. The composition according to any one of claims 17-20, wherein the one or more saturated C' s₂-C₂₀The aliphatic hydrocarbyl dicarboxylic acid is sebacic acid.

23. The composition according to any of the preceding claims 1-4 or 6 or 8-10 or 12-14 or 17-21, wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

24. A composition according to claim 5, wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

25. The composition according to claim 7, wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

26. A composition according to claim 11 wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

27. The composition according to claim 15, wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

28. The composition according to claim 16, wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

29. The composition according to claim 22, wherein the oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate is zinc dihydrocarbyl dithiophosphate.

30. A method of lubricating a spark-ignited or compression-ignited internal combustion engine comprising lubricating the engine with a lubricating oil composition according to any preceding claim 1 to 29.

31. Use of an effective minor amount of an oil-soluble or oil-dispersible polymeric friction modifier (B) as defined in any one of claims 1 to 29 as an additive in the lubrication of a spark-ignited or compression-ignited internal combustion engine to reduce and/or inhibit corrosion of non-ferrous metal containing engine components during operation of the engine in a lubricating oil composition comprising a major amount of an oil of lubricating viscosity.

32. Use according to claim 31, wherein the engine component comprising a non-ferrous metal comprises copper, lead or an alloy of such metals.

33. Use according to claim 31 or 32, wherein the lubricating oil composition further comprises as an additive an effective minor amount of an oil-soluble or oil-dispersible metal dihydrocarbyl dithiophosphate (C) as defined in any one of claims 1 to 29.