ES2382839T3 - Use of a combustion engine lubricant composition containing dispersant additive and viscosity index improver of the polymer dispersant to enhance antiwear properties - Google Patents

Abstract

A multigrade lubricating oil composition with enhanced anti-wear properties for use in an internal combustion engine comprises (a) a base oil comprising at least 90 % by weight of the base oil, of one or more basestocks selected from the group consisting of base stocks derived from Fischer-Tropsch synthesised, waxy, paraffinic hydrocarbon material by processes comprising hydrocracking and/or hydroisomerisation, Group II basestocks, Group III basestocks and mixtures thereof; (b) one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8 % by weight of the composition; and (c) one or more dispersants in a total amount of active dispersants of 1.5 to 3 % by weight of the composition.

Description

Use of a combustion engine lubricant composition containing dispersant additive and viscosity index improver of the polymer dispersant to enhance antiwear properties.

This invention relates to the use of multigrade lubricating oil compositions in internal combustion engines to improve the antiwear properties of such compositions.

The lubricating oil compositions for use in internal combustion engines comprise a basic oil and one or more additives. The basic oils may comprise one or more base oils.

The additives present in the lubricating oil compositions for internal combustion engines usually comprise one or more dispersants. The purpose of the dispersants in the lubricating oil compositions is to keep the oil soluble combustion products in suspension to avoid or reduce the formation of deposits on the metal surfaces, the thickening of the oil and the deposition of mud in the engine.

The use of dispersants can increase the viscosity of the lubricating oil composition. Therefore, generally, the higher the concentration of dispersant used in a lubricating oil composition, the lower the viscosity of the basic oil that should be used to achieve a lubricating oil composition with the required viscosity. The lower viscosity base oils generally have higher volatility and their use in lubricating oil compositions for internal combustion engines may result in unacceptable wear, for example in the bearings and / or valve train of the internal combustion engine. Therefore, it is desirable to reduce the amount of dispersant that is required to provide a lubricating oil of the desired performance, so that a basic oil having a viscosity that reduces or at least mitigates those effects can be used.

US 5719107 refers to a lubricating oil for use in heavy duty diesel engines comprising a mixture of (A) a majority of an oil of lubricating viscosity, (B) at least 4% by mass of dispersant, (C) at least 0.3% by mass of a metal phenate, (D) less than 0.1% by mass of friction modifier, (E) less than 0.3% by mass of sulphured phenols and (F) less than 0.12% neutral calcium sulphonate. According to this document:

“In multigrade oils that have dispersant viscosity modifiers, the dispersant can be used at a somewhat lower treatment rate. In this case, the dispersant viscosity modifier serves as an additional dispersant. At least one group of researchers (US Patent No. 5,294,354 issued to Papke et al.) Has reported a particular dispersant viscosity modifier formulation in which the treatment rate of a conventional dispersant is zero. In that case, the dispersant viscosity modifier serves as a dispersant. ”

According to US5719107, the dispersant may be present in the range of 4-8% by mass.

US 5958848 seeks to reduce the amount of chlorine that dispersants contain in multigrade crankcase lubricants. It refers to the use of multifunction viscosity modifiers to provide the dispersion lost by decreasing the amount of dispersant containing chlorine, rather than using unconventional dispersants. According to US 5958848:

“The viscosity modifiers are materials added to crankcase lubricants to confer operability at low and high temperatures. The viscosity modifiers that have been subsequently reacted to provide dispersion are known as multifunctional viscosity modifiers or dispersant viscosity modifiers. ”

According to US 5958848, the amount of viscosity modifier used as an active component in the oil is generally from 0.01 to 6% by weight, and more preferably from 0.1 to 2% by weight. The amount of dispersant is said to be in the range of 1.5 to 3.0% by weight.

According to US 5958848, the base oils used in the lubricating oil may be selected from any of the natural or artificial oils used as crankcase lubricating oils for spark ignition and compression ignition engines. The base oil of the lubricating oil is said to have a kinematic viscosity of 2.5 to 12 mm2 / s and preferably 2.5 to 9 mm2 / s at 100 ° C. However, US5958848 says nothing about the nature of the base oil used in fully formulated oils in the examples described herein.

US4925579 refers to lubricating oil compositions containing oil-soluble hydroperoxidized polymeric additives that are said to improve the sludge and dispersion of the varnish as well as improve the viscosity index characteristics of the lubricating oil. Formulated 10W-40 oils containing additives are shown in Table I. The effectiveness of the additives in the oil was measured in terms of protection provided against deposits and wear of the valve train in a phase 9-2 of the method of VD Sequence test (according to the candidate test for ASTM).

EP-1191089-A refers to low viscosity lubricating oil compositions which, as stated herein, can use a mineral or synthetic oil base oil of lubricating viscosity selected from the group consisting of group base oils I, II, III, IV and V and mixtures thereof.

EP-1538193-A refers to the improvement of soot-induced kinematic viscosity of lubricating oil compositions by the combined use of derivatized and dispersing high molecular weight olefin copolymers containing high molecular weight nitrogen.

There remains a need for a lubricating oil composition that reduces or at least mitigates at least some of the problems identified above.

Therefore, according to the present description the use of a multigrade lubricating oil composition in an internal combustion engine is provided, a composition comprising:

(to)

 a basic oil comprising at least 90% by weight of the basic oil of one or more base oils selected from the group consisting of group II base oils;

(b)

 one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the composition;

(C)

 one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition;

(d)

 one or more detergents in a total active concentration of 1 to 5% by weight of the composition; Y

(and)

 one or more metal dihydrocarbyl dithiophosphates in a total amount expressed as phosphorus of 0.01 to 82% by weight of the composition.

Therefore, the present invention solves the technical problem defined above by using a combination of the defined basic oil, one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the composition and one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition.

It has been found that a lubricating oil composition that meets API CH-4 or greater can be formulated by selecting the defined basic oil, using one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the lubricating oil composition and the use of one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition. The API standard is defined according to ASTMD 4485.

It has also been found that the lubricating oil composition of the use of the present invention exhibits good antiwear properties. In particular, it has been found that the lubricating oil composition unexpectedly reduces the wear of the valve train of an internal combustion engine, which is preferably a diesel engine, more preferably a heavy duty diesel engine.

Therefore, according to another aspect of the present invention, use is provided in a multigrade lubricating oil composition comprising one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition, one or more more detergents and one or more metal dihydrocarbyl dithiophosphates, of

(i)

 one or more dispersant viscosity modifiers in an amount of 0.15 to 0.8% by weight of the composition, in combination with

(ii)

 a basic oil comprising at least 90% by weight of the basic oil of one or more base oils selected from the group consisting of group II base oils,

to enhance the antiwear properties of the lubricating oil composition and preferably to enhance the wear properties with respect to the wear of the valve train of an internal combustion engine which is preferably a diesel engine and more preferably a heavy duty diesel engine.

Furthermore, according to another aspect of the present description, there is provided a method of reducing the wear of the valve train of an internal combustion engine, which is preferably a diesel engine and more preferably a heavy duty diesel engine, a method comprising lubricating the heavy duty diesel engine with a multigrade lubricating oil composition comprising:

(a) a basic oil comprising at least 90% by weight of basic oil of one or more base oils 5 selected from the group consisting of group II base oils;

(b)

 one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the lubricating oil composition;

(C)

 one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition;

(d)

 one or more detergents; in a total active concentration of 1 to 5% by weight of the composition; Y

10 (e) one or more metal dihydrocarbyl dithiophosphates, in a total amount expressed as phosphorus of 0.01 to 0.2% by weight of the composition.

Basic oil

The basic oil of the lubricating oil composition of the present invention comprises at least 90% by weight of the basic oil of one or more base oils selected from the group consisting of group II base oils.

15 Group II base oils are defined according to API 1509, "ENGINE OIL CERTIFICATION AND LICENSE SYSTEM", November 2004 version 15th edition appendix E, as base oils having a saturated hydrocarbon content of at least 90%, by weight, a sulfur content of not more than 0.03% by weight and a viscosity index of at least 80 and less than 120. Group III base oils are defined according to the same API 1509 standard as base oils that have a saturated hydrocarbon content of at least 90%

20 by weight, a sulfur content of not more than 0.03% by weight and a viscosity index of at least 120. Group II base oils include group II + base oils that are group II base oils with an index of viscosity from 110 to 120.

The base oils of group II and group III are derived from mineral oils by known methods comprising hydrocracking and / or hydroisomerization.

Base oils derived from the paraffinic, waxy, synthesized Fischer-Tropsch hydrocarbon material can be prepared by methods comprising hydrocracking and / or hydroisomerization known in the art, for example as described in WO 00/14187, WO02 / 064710, WO 2005/066314 and US 6008164.

Therefore, the selected base oils used in the present invention are highly saturated. The selected base oils used in the present invention each have a saturated hydrocarbon content of at

30 minus 90% by weight.

Preferably, the basic oil has a kinematic viscosity at 100 ° C in the range of 2.5 to 12 mm2 / s, more preferably in the range of 2.5 to 9 mm2 / s, even more preferably in the range of 4 to 8 mm2 / s and most preferably in the range of 4.5 to 7.5 mm2 / s. The kinematic viscosity can be measured according to ASTM D445.

It has been found that the kinematic viscosity of the basic oil that can be used to prepare a lubricating oil composition of a defined viscosity according to the present invention may be greater than that of a basic oil that could otherwise be used to prepare an oil composition. lubricant with a higher concentration of dispersant than that used in the present invention. For example, a basic oil having a kinetic viscosity at 100 ° C of 7 to 7.5 mm2 / s can be used to prepare a multigrade lubricating oil composition

40 according to the present invention of grade 15W40 while using conventional amounts of dispersant a basic oil with a kinematic viscosity at 100 ° C of 6 to 6.7 mm2 / s should be used to prepare a 15W40 multigrade lubricating oil composition. In general, it has been found that multigrade lubricating oil compositions of the present invention can be prepared using basic oils having kinematic viscosities that are in the region of 0.5 mm 2 / s greater than the kinetic viscosities of oils

Basic ones that would be used with conventional formulations for multi-grade lubricating oil formulations of the same grade.

An advantage of using basic oils with a higher kinematic viscosity is that they tend to reduce oil consumption when the lubricating oil composition is used to lubricate an internal combustion engine and / or to enhance the antiwear properties of the lubricating oil composition.

The basic oil may comprise minor amounts (i.e., less than 10% by weight of the basic oil) of other base oils, for example group I base oils.

The dispersant viscosity modifier.

The one or more dispersant viscosity modifiers are present in the lubricating oil composition in a total amount of 0.15 to 0.8% by weight of the lubricating oil composition, preferably in a total amount of 0.2 to 0.4% by weight of the lubricating oil composition, for example in a total amount of 0.25 to 0.3% by weight of the lubricating oil composition.

Each dispersant viscosity modifier may comprise more than one oil-soluble polymeric hydrocarbon main structure, each having one or more functional groups that can be associated with particles to be dispersed. Each of the functionalized polymeric hydrocarbon main structures can be functionalized with one or more functional groups incorporated in the main structure or with one or more pendant functional groups of the main polymer structure. Typical functional groups may be polar and may contain one or more heteroatoms, for example phosphorus, oxygen, sulfur, nitrogen, halogen or boron. An example of a suitable dispersant viscosity modifier is an ethylene-propylene copolymer grafted with an active monomer, for example maleic anhydride and then derivatized with an alcohol or an amine. The preparation of such dispersant viscosity modifiers is described for example in US 4089794, US4160739 and US4137185. Other dispersant viscosity modifiers that can be used are ethylene or propylene copolymers reacted or grafted with nitrogen compounds, for example as described in US 4068056, US4068058, US 4146489 and US 4149984. Other viscosity modifiers of dispersants that can be used are graft copolymers, for example as described in WO96 / 12746 and WO 99/21902.

A suitable dispersant viscosity modifier is present in LZ 7177B of Lubrizol, which is an additive concentrate that contains approximately 10% by weight of dispersant viscosity modifier. The additive concentrate LZ7177B can be suitably used in an amount of approximately 2.5% by weight in the lubricating oil composition to give a dispersant viscosity modifier concentration of approximately 0.21% by weight in the composition of lubricant oil.

The one or more dispersant viscosity modifiers with one or more surfactants can be used. These can stabilize the dispersant.

Dispersants

The one or more dispersants are present in the lubricating oil composition in a total amount of active dispersants of 1.5 to 3% by weight of the lubricating oil composition, preferably in a total amount of active dispersants of 2 to 2.5 % by weight of the lubricating oil composition.

Each dispersant comprises one or more, preferably at least two, oil-soluble polymeric hydrocarbon main structures, each having one or more functional groups that can be associated with particles to be dispersed. The functional groups may be amine, alcohol, amide or ester groups.

Suitable dispersants are, for example, oil-soluble salts, esters, amino esters, amides, imides and oxazolines of mono and dicarboxylic acids substituted with long chain hydrocarbons and their anhydrides; long-chain hydrocarbon thiocarboxylate derivatives; long chain aliphatic hydrocarbons having a polyamine directly attached thereto; Mannich condensation products formed by the condensation of a long chain substituted phenol with formaldehyde, polyalkylene polyamine; Koch reaction products and the like.

The oil-soluble polymeric hydrocarbon main structure is usually an olefin polymer, especially a polymer comprising more than 50 mol% of a C2 to C18 olefin, typically more than 50 mol% of a C2 to C5 olefin. The oil soluble polymeric hydrocarbon main structure may be a homopolymer or a copolymer of two or more olefins. A preferred class of olefin polymers are polybutenes and more preferably polyisobutenes. Other preferred classes of olefin polymers are ethylene-alpha-olefin copolymers, alpha-olefin homopolymer and alpha-olefin copolymers. The oil-soluble polymeric hydrocarbon main structure normally has a number average molecular weight (Mn) in the range of 300 to 20,000, preferably 500 to 10,000, more preferably 700 to 5,000. The molecular weight can be determined by gel permeation chromatography.

The oil-soluble polymeric hydrocarbon main structure can be functionalized with one or more functional groups incorporated in the chain or with one or more pendant functional groups of the polymer chain.

Typical functional groups may be polar and may contain one or more heteroatoms, for example phosphorus, oxygen, sulfur, nitrogen, halogen or boron.

Preferred dispersants are polyisobutenylsuccinimide dispersants. Suitable dispersants can be provided in one or more additive concentrates that can be used to provide a total active dispersant concentration of about 2.1% by weight in the lubricating oil composition.

Other additives

The lubricating oil composition additionally comprises one or more detergents and one or more metal dihydrocarbyldithiophosphates.

The lubricating oil composition may also optionally comprise one or more additional additives. Examples of such additives are surfactants, friction modifiers, complementary antiwear agents, antioxidants, corrosion inhibitors, pour point reducers, anti-foaming agents, demulsifiers, elastomer compatibility adjuvants and combinations thereof.

Detergents

One or more detergents are present in the lubricating oil composition. Suitable detergents are

15 ash-free detergents, metal salt detergents and combinations thereof. Suitable metal salt detergents are neutral and excess base phenates, sulphonated phenates, sulfonates, carboxylates, salicylates and combinations thereof. The metals of the salts may be alkali metals, alkaline earth metals and combinations thereof. Preferably, the metals are calcium, magnesium and combinations thereof. Detergent salts of both calcium and magnesium may be present in the lubricating oil composition. Suitable metal detergents are neutral and excess base salts with a TBN (total basic number, "total base number", measured by ASTM2896) in the range of 20 to 450. Suitable calcium sulphonates may have TBN values (total basic number) of 85, 300 and 400. Suitable calcium phenates may have TBN values of 150 and 250. The one or more detergents are present in the lubricating oil composition in a total active concentration of 1 to 5% by weight of the composition. The one or more

25 metal salt detergents may be present in the lubricating oil composition in a total amount of metal salt of 0.5 to 3% by weight of the composition.

Metal dihydrocarbyl dithiophosphates.

One or more metal dihydrocarbyl dithiophosphates are present in the lubricating oil composition. These compounds can be used as antiwear agents and / or antioxidants. Suitable metals in these compounds are, for example, alkali metals, alkaline earth metals, zinc, aluminum, lead, tin, molybdenum, manganese, nickel and copper, most preferably zinc. Primary and / or secondary hydrocarbyl groups may be present in these compounds. Each hydrocarbyl group can have 1 to 18 carbon atoms. The one or more metal dihydrocarbyl dithiophosphates are present in the lubricating oil composition in a total amount, expressed as phosphorus, of 0.01 to 0.2% by weight of the composition.

35 Friction modifiers.

The one or more surfactants that may optionally be present with the dispersant viscosity modifier in the lubricating oil composition may exhibit friction modifying properties. Additionally or alternatively, one or more other friction modifiers may be present in the lubricating oil composition. Suitably, such other friction modifiers are for example, mono and diamines that can be used as such or in the form of an adduct or reaction product with a boron compound. Other suitable friction modifiers are esters formed by reacting carboxylic acids or anhydrides with alkanols. Suitable friction modifiers are, for example, molybdenum dithiocarbamate, oleylamide and monooleate and glycerol dioleate. The one or more friction modifiers may be present in the lubricating oil composition in a total amount of less than 1% by weight of the composition.

45 Other complementary antiwear agents.

The one or more dispersant viscosity modifiers and the one or more detergents present in the lubricating oil composition may have antiwear properties.

One or more complementary antiwear agents may optionally be present in the lubricating oil composition. Suitable complementary antiwear agents are for example boron compounds, salicylates and combinations thereof. The one or more complementary antiwear agents may be present in the lubricating oil composition in a total amount of up to 2% by weight of the composition.

Antioxidants

One or more antioxidants may be present in the lubricating oil composition. Suitable antioxidants are, for example, hindered phenols, alkaline earth metal salts of alkylphenol thioesters which preferably have C5 to C12 alkyl side chains, nonylphenol calcium sulphide, dodecylphenol calcium sulphide,

5 oil-soluble phenates, oil-soluble sulfurized phenates, phosphosulphurized hydrocarbons, sulfurized hydrocarbons (for example, sulfurized olefins), phosphorus esters, metal thiocarbamates, oil-soluble copper compounds (for example, as described in US4867890) , compounds containing molybdenum and the like. The one or more antioxidants may be present in the lubricating oil composition in a total amount of up to 5% by weight of the lubricating oil composition.

10 Corrosion inhibitors.

One or more corrosion inhibitors may optionally be present in the lubricating oil composition. Suitable corrosion inhibitors are for example nonionic polyalkylene polyols and esters thereof, polyoxyalkylenephenols, triazoles, anionic alkylsulfonic acids and the like. The one or more corrosion inhibitors may be present in the lubricating oil composition in a total amount of up to 1% in

15 weight of the lubricating oil composition.

Pour point reducers.

One or more pour point reducers may optionally be present in the lubricating oil composition. Suitable pour point reducers are for example methacrylates, alkyl methacrylates, vinyl fumarates, styrene esters and the like. The one or more pour point reducers may be

20 present in the lubricating oil composition in a total amount of up to 1% by weight of the lubricating oil composition.

Antifoaming agents.

One more antifoaming agents may optionally be present in the lubricating oil composition. Suitable antifoaming agents are for example siloxanes, dimethylsiloxanes, phenylmethylsiloxanes, acrylates and

25 similar. The one or more antifoaming agents may be present in the lubricating oil composition in a total amount by weight usually 10 to 100 ppm of the lubricating oil composition.

Adjuvants of compatibility with elastomers.

One or more adjuvants of elastomer compatibility may optionally be present in the lubricating oil composition. Compatibility adjuvants with suitable elastomers are for example

30 long chain organic acids and the like. The one or more adjuvants of elastomer compatibility may be present in the lubricating oil composition in a total amount of up to 1% by weight of the lubricating oil composition.

Demulsifiers.

One or more demulsifiers may optionally be present in the lubricating oil composition.

Suitable demulsifiers are for example ethoxylated compounds and the like. The one or more demulsifiers may be present in the lubricating oil composition in a total amount by weight of up to 1000 pm of the lubricating oil composition.

A suitable lubricating oil composition according to the present invention may comprise:

one or more dispersant viscosity modifiers in a total active dispersant concentration of 0.15 40 to 0.8% by weight of the composition;

one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition;

one or more detergents in a total amount of 1 to 5% by weight of the composition;

one or more metal dihydrocarbyl dithiophosphates in a total amount expressed as phosphorus of 0.01 to 0.2% by weight of the composition;

Optionally, one or more friction modifiers that, if present, are present in a total amount of less than 1% by weight of the composition;

optionally one or more complementary antiwear agents which, if present, are present in a total amount of up to 2% by weight of the composition;

optionally one or more antioxidants that, if present, are present in a total amount of up to 5% by weight of the composition;

optionally one or more corrosion inhibitors which, if present, are present in a total amount of up to 1% by weight of the composition;

optionally one or more pour point reducers which, if present, are present in a total amount of up to 1% by weight of the composition;

optionally one or more antifoaming agents that, if present, are present in a total amount by weight of 10 to 100 ppm of the composition;

optionally one or more adjuvants for compatibility with elastomers which, if present, are present in a total amount of up to 1% by weight of the composition;

and optionally one or more demulsifiers that, if present, are present in a total amount of up to 1000 ppm of the composition;

the rest of the composition being a basic oil comprising at least 90% by weight of the basic oil of one or more base oils selected from the group comprising base oils derived from paraffinic, waxy, synthesized hydrocarbon material from Fischer-Tropsch by procedures that they comprise hydroisomerization and / or hydrocracking, group II base oils, group III base oils and mixtures thereof.

The lubricating oil composition of the present invention can be prepared by combining the basic oil with one or more additive concentrates comprising the additives, by methods known in the art.

An advantage of the present invention is that it allows using a basic oil with a kinematic viscosity greater than conventional lubricating oil formulations with higher dispersant concentrations. This can result in a lubricating oil composition with low Noack volatility. A kinematic viscosity of the high basic oil and a low Noack volatility of the lubricating oil can result in a lubricating oil composition that when used to lubricate an internal combustion engine exhibits improved oil consumption and / or wear performance of the train of upper valves.

The lubricating oil composition of the present invention is suitable for use in an internal combustion engine, preferably a diesel engine and more preferably a heavy duty diesel engine.

The lubricating oil composition may have a Noack volatility value in the range of 5 to 13% by weight. Noack volatility can be measured using the D5800 or IP 421 method or the CEC-L-40-A-93 methods.

The present invention uses a basic oil with a kinematic viscosity and a combination of additives that help maintain a layer of lubricating film in an internal combustion engine in which it is used. In particular, this can help reduce the wear of moving parts in the motor that are subjected to metal-to-metal contact and therefore that are vulnerable to wear under high load and / or high soot concentrations, for example in a diesel engine and in particular in a heavy duty diesel engine. For example, wear on the injector screws in the valve train of a diesel engine can lead to incomplete combustion of the fuel and loss of power. Wear of the crosshead in a diesel engine can lead to the valves not opening or closing completely, which in turn can lead to a reduction in engine performance. The lubricating oil of the present invention helps mitigate these wear problems. In particular, the lubricating oil of the present invention has been shown to provide excellent protection against wear of the valve train, protection against wear of the roller follower and protection against wear of the ring / liner according to the tests of the API industry standard . This allows a lubricating oil composition to be formulated that complies with API CH-4 or greater, for example CI-4 or CJ-4.

The lubricating oil composition of the present invention may be a lubricating oil composition 0W20, 0W30, 0W40, 5W20, 5W30, 5W40, 10W30, 10W40, 10W50, 10W60, 15W30, 15W40, 15W50, 20W40, 20W50, 25W50 or 25W60.

The invention will now be described by way of example with reference only to the following examples and with reference to Figure 1 which is a graph of the wear rates obtained in an engine test using a lubricating oil composition according to the present invention in comparison With a conventional lubricating oil composition that meets API CJ-4.

Cummins ISM engine test.

A lubricating oil composition was prepared according to the present composition (example 1) and a lubricating oil composition (composition A) was prepared for comparison. Composition A was a commercially available lubricating oil composition that meets API CJ-4 specifications. The composition of the lubricating oil composition used in Example 1 is shown in Table 1.

Table 1.

Components (% by weight)

Concentration of Example 1 (% by weight)

Viscosity modifier of dispersant olefin copolymer, LZ7177B

2.50 (of which 10% is active)

Oil dispersant for cars with low chlorine content and high molecular weight succinimide dispersant PIB

4.20 (corresponding to 2.1% by weight of active dispersant in the composition)

Mixture of calcium phenate and sulphonate detergents

2.93

Primary and secondary zinc dialkyl dithiophosphate antiwear additives

0.91 (corresponding to approximately 0.09% by weight of phosphorus in the composition)

Other additives: antioxidant, compatibility agent, yellow metal passivators, diluent oil, amide friction modifier, polymer viscosity modifier and pour point reducer.

0.78

Basic oil (group II base oils Jurong 150N at 46% and Jurong 500 N at 45%)

88.69

Each oil was evaluated in a Cummins ISM 2002 heavy duty diesel engine with unit injectors

10 electronically controlled. In each test, the lubricating oil composition was used to lubricate the engine while running for 200 hours with a fuel having a maximum sulfur content of 500 ppm.

The engines were run in each test to a typical maximum soot content in the oil of 6% by weight and then the wear rates were interpolated to determine the wear rate to a soot content

15 in oil 4.6% by weight.

The results are shown graphically in Figure 1 which shows that although the conventional lubricating oil composition (comparison A) exceeded the wear criteria of CJ-4, the lubricating oil composition according to the present invention was superior and exhibited less wear. as measured by the weight loss of the crosshead, the weight loss of the upper ring and the weight loss of the adjustment screws.

Claims (7)

1. Use in a multigrade lubricating oil composition comprising one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition, one or more detergents present in the lubricating oil composition in a concentration active total of 1 to 5% by weight of the composition and one or 5 plus metal dihydrocarbyl dithiophosphates present in the lubricating oil composition in a total amount, expressed as phosphorus, of 0.01 to 0.2% by weight of the composition, from (i) one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the composition, in combination with 10 (ii) a basic oil comprising at least 90% by weight of the basic oil of one or more base oils selected from the group consisting of group II base oils, to enhance the antiwear properties of the lubricating oil composition. 2. Use according to claim 1, wherein one or more dispersants are present in the oil composition lubricant in a total amount of active dispersants of 1.5 to 2.5% by weight of the lubricating oil composition. 3. Use according to claim 2, wherein one or more dispersants are present in the lubricating oil composition in a total amount of active dispersants of 2 to 2.5% by weight of the lubricating oil composition. 4. Use according to claim 3, wherein one or more dispersants are present in the lubricating oil composition in a total amount of active dispersants of 2.1% by weight of the lubricating oil composition.

5.

Use according to any one of the preceding claims, enhancing the use of antiwear properties with respect to the wear of the valve train of an internal combustion engine.

6.

Use according to claim 5, wherein the internal combustion engine is a diesel engine.

7.

Use according to claim 6, wherein the internal combustion engine is a heavy duty diesel engine.