WO2016046133A1

WO2016046133A1 - Lubricating composition

Info

Publication number: WO2016046133A1
Application number: PCT/EP2015/071605
Authority: WO
Inventors: Mark Clift Southby; Sergio De Rooy
Original assignee: Shell Internationale Research Maatschappij B.V.; Shell Oil Company
Priority date: 2014-09-22
Filing date: 2015-09-21
Publication date: 2016-03-31
Also published as: RU2017113940A3; RU2017113940A; EP3197986B1; JP6971149B2; JP2017528588A; RU2709211C2; BR112017005843A2; CN107075403A; EP3197986A1

Abstract

Use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising C₁₂-C₂₄ fatty acid and C₁₂-C₂₄ fatty amine for providing reduced wear.

Description

LUBRICATING COMPOSITION

The present invention relates to a lubricating composition, in particular to a lubricating composition which is suitable for lubricating internal combustion engines and which has improved friction and wear

reduction and improved fuel economy.

Increasingly severe automobile regulations in respect of emissions and fuel efficiency are placing increasing demands on both engine manufacturers and lubricant formulators to provide effective solutions to improve fuel economy.

Optimising lubricants through the use of high performance basestocks and novel additives represents a flexible solution to a growing challenge.

Friction-reducing additives (which are also known as friction modifiers) are important lubricant components in reducing fuel consumption and various such additives are already known in the art .

Friction modifiers can be conveniently divided into two categories, that is to say, metal-containing friction modifiers and ashless (organic) friction modifiers.

Organo-molybdenum compounds are amongst the most common metal-containing friction modifiers. Typical organo-molybdenum compounds include molybdenum

dithiocarbamates (MoDTC) , molybdenum dithiophosphates (MoDTP), molybdenum amines, molybdenum alcoholates, and molybdenum alcohol-amides . WO1998026030, WO1999031113, WO1999047629 and WO1999066013 describe tri-nuclear molybdenum compounds for use in lubricating oil

compositions . However, the trend towards low-ash lubricating oil compositions has resulted in an increased drive to achieve low friction and improved fuel economy using ashless friction modifiers.

Ashless (organic) friction modifiers which have been used in the past typically comprise esters of fatty acids and polyhydric alcohols, fatty acid amides, amines derived from fatty acids and organic dithiocarbamate or dithiophosphate compounds .

Unfortunately, however, lubricant additives which are used to reduce friction, do not typically also reduce wear. Typical additives for reducing wear contain both phosphorus and sulphur. However, since phosphorus and/or sulphur containing additives can potentially poison catalysts in engine after-treatment systems, such additives are undesirable at higher levels.

In order to reduce both friction and wear, both a friction modifier and an anti-wear agent, such as a phosphorus- or sulphur-containing anti-wear agent, typically needs to be added to the lubricant formulation. As mentioned above, however, such a formulation may suffer from disadvantages such as poisoning of catalyst in engine after-treatment systems . Therefore it would be desirable to provide a lubricating composition which does not contain phosphorus- and sulphur-containing additives, or which contains low levels of such additives, but which still provides reduced friction and wear.

It has now surprisingly been found by the present inventors that certain ashless additives which are known for use as friction modifiers in lubricating compositions can also be used to reduce wear, while obviating the need to include high levels of phosphorus- and sulphur- containing additives. It has also been surprisingly found that the lubricating composition of the present invention provides improved fuel economy properties .

Accordingly, the present invention provides the use of a lubricating composition comprising (i) base oil and

(ii) ashless friction modifier comprising Ci₂-C₂4 fatty acid and Ci₂-C₂4 fatty amine for providing reduced wear.

According to a second aspect of the present

invention, there is provided the use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂₄ fatty acid and Ci₂-C₂₄ fatty amine for providing reduced friction and reduced wear .

According to a further aspect of the present invention, there is provided the use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂₄ fatty acid and Ci₂-C₂₄ fatty amine for providing reduced wear in the presence of soot .

According to yet a further aspect of the present invention there is provided the use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂ fatty acid and Ci₂-C₂ fatty amine for providing reduced friction and wear in the presence of soot.

According to yet a further aspect of the present invention, there is provided the use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂ fatty acid and Ci₂-C₂ fatty amine for providing improved fuel economy.

The ashless friction modifier for use herein comprises a mixture of Ci₂-C₂ fatty acid and Ci₂-C₂ fatty amine . The fatty acid component of the ashless friction modifier is preferably a C14-C₂₂ fatty acid, more

preferably a Ci₆-C₂o fatty acid, even more preferably a Ci₈ fatty acid. Preferably, the Ci₂-C₂4 fatty acid is an unsaturated fatty acid. In a particularly preferred embodiment, the fatty acid component is oleic acid.

The fatty amine component of the ashless friction modifier is preferably a C14-C₂₂ fatty amine, more

preferably a Ci₆-C₂o fatty amine, even more preferably a Ci8 fatty amine. Preferably, the Ci₂-C₂4 fatty amine is an unsaturated fatty amine. In a preferred embodiment, the Ci₂-C₂4 fatty amine is a primary amine. In a particular preferred embodiment, the fatty amine component is oleyl amine .

In preferred embodiments, the ashless friction modifier additionally comprises a Ci₂-C₂₄ fatty amide.

If present, the fatty amide component of the ashless friction modifier is preferably a Ci₄-C₂₂ fatty amide, more preferably a Ci₆-C₂₀ fatty amide, even more

preferably a Ci₈ fatty amide. Preferably, the Ci₂-C₂₄ fatty amide is an unsaturated fatty amide. In a particular preferred embodiment, the fatty amide component is oleyl amide .

A suitable ashless friction modifier for use in the present invention is Additin M10229, commercially available from Rhein Chemie .

The ashless friction modifier described above is preferably present at a level of from 0.05 wt% to 3 wt%, more preferably at a level of from 0.1 wt% to 1 wt%, even more preferably at a level of from 0.5 wt% to 1 wt%, by weight of the lubricating composition.

There are no particular limitations regarding the base oil used in lubricating composition according to the present invention, and various conventional mineral oils, synthetic oils as well as naturally derived esters such as vegetable oils may be conveniently used.

The base oil used in the present invention may conveniently comprise mixtures of one or more mineral oils and/or one or more synthetic oils; thus, according to the present invention, the term "base oil" may refer to a mixture containing more than one base oil, including at least one Fischer-Tropsch derived base oil. Mineral oils include liquid petroleum oils and solvent-treated or acid-treated mineral lubricating oil of the paraffinic, naphthenic, or mixed paraffinic/naphthenic type which may be further refined by hydrofinishing processes and/or dewaxing .

Suitable base oils for use in the lubricating oil composition of the present invention are Group I-III mineral base oils (preferably Group III), Group IV poly- alpha olefins (PAOs), Group II-III Fischer-Tropsch derived base oils (preferably Group III), Group V ester base oils, and mixtures thereof.

By "Group I", "Group II" "Group III" and "Group IV" and "Group V" base oils in the present invention are meant lubricating oil base oils according to the

definitions of American Petroleum Institute (API) for categories I, II, III, IV and V. These API categories are defined in API Publication 1509, 15th Edition, Appendix E, April 2002.

Fischer-Tropsch derived base oils are known in the art . By the term "Fischer-Tropsch derived" is meant that a base oil is, or is derived from, a synthesis product of a Fischer-Tropsch process. A Fischer-Tropsch derived base oil may also be referred to as a GTL (Gas-To-Liquids ) base oil. Suitable Fischer-Tropsch derived base oils that may be conveniently used as the base oil in the

lubricating composition of the present invention are those as for example disclosed in EP0776959, EP0668342, WO1997021788, WO2000015736, WO2000014188, WO2000014187, WO2000014183, WO2000014179, WO2000008115, WO1999041332,

EP1029029, WO2001018156 and WO2001057166.

Typically, the aromatics content of a Fischer- Tropsch derived base oil, suitably determined by ASTM D 4629, will typically be below 1 wt.%, preferably below 0.5 wt . % and more preferably below 0.1 wt.%. Suitably, the base oil has a total paraffin content of at least 80 wt.%, preferably at least 85, more preferably at least 90, yet more preferably at least 95 and most preferably at least 99 wt.%. It suitably has a saturates content (as measured by IP-368) of greater than 98 wt.%. Preferably the saturates content of the base oil is greater than 99 wt.%, more preferably greater than 99.5 wt.%. It further preferably has a maximum n-paraffin content of 0.5 wt.%. The base oil preferably also has a content of naphthenic compounds of from 0 to less than 20 wt.%, more preferably of from 0.5 to 10 wt.%.

Typically, the Fischer-Tropsch derived base oil or base oil blend has a kinematic viscosity at 100°C (as measured by ASTM D 7042) in the range of from 1 to 30 mm²/s (cSt), preferably from 1 to 25 mm²/s (cSt), and more preferably from 2 mm²/s to 12 mm²/s. Preferably, the Fischer-Tropsch derived base oil has a kinematic

viscosity at 100°C (as measured by ASTM D 7042) of at least 2.5 mm²/s, more preferably at least 3.0 mm²/s. In one embodiment of the present invention, the Fischer-

Tropsch derived base oil has a kinematic viscosity at 100°C of at most 5.0 mm²/s, preferably at most 4.5 mm²/s, more preferably at most 4.2 mm²/s (e.g. "GTL 4") . In another embodiment of the present invention, the Fischer- Tropsch derived base oil has a kinematic viscosity at 100°C of at most 8.5 mm²/s, preferably at most 8 mm²/s (e.g. "GTL 8") .

Further, the Fischer-Tropsch derived base oil typically has a kinematic viscosity at 40°C (as measured by ASTM D 7042) of from 10 to 100 mm²/s (cSt), preferably from 15 to 50 mm²/s .

Also, the Fischer-Tropsch derived base oil

preferably has a pour point (as measured according to

ASTM D 5950) of below -30°C, more preferably below -40°C, and most preferably below -45°C.

The flash point (as measured by ASTM D92) of the Fischer-Tropsch derived base oil is preferably greater than 120°C, more preferably even greater than 140°C.

The Fischer-Tropsch derived base oil preferably has a viscosity index (according to ASTM D 2270) in the range of from 100 to 200. Preferably, the Fischer-Tropsch derived base oil has a viscosity index of at least 125, preferably 130. Also it is preferred that the viscosity index is below 180, preferably below 150.

In the event the Fischer-Tropsch derived base oil contains a blend of two or more Fischer-Tropsch derived base oils, the above values apply to the blend of the two or more Fischer-Tropsch derived base oils.

The lubricating oil composition preferably comprises 80 wt% or greater of Fischer-Tropsch derived base oil.

Synthetic oils include hydrocarbon oils such as olefin oligomers (including polyalphaolefin base oils; PAOs), dibasic acid esters, polyol esters, polyalkylene glycols (PAGs), alkyl naphthalenes and dewaxed waxy isomerates. Synthetic hydrocarbon base oils sold by the Shell Group under the designation "Shell XHVI" (trade mark) may be conveniently used.

Poly-alpha olefin base oils (PAOs) and their manufacture are well known in the art . Preferred poly- alpha olefin base oils that may be used in the

lubricating compositions of the present invention may be derived from linear C₂ to C₃₂, preferably C₆ to Ci₆, alpha olefins. Particularly preferred feedstocks for said poly- alpha olefins are 1-octene, 1-decene, 1-dodecene and 1- tetradecene.

There is a strong preference for using a Fischer- Tropsch derived base oil over a PAO base oil, in view of the high cost of manufacture of the PAOs. Thus,

preferably, the base oil contains more than 50 wt.%, preferably more than 60 wt.%, more preferably more than

70 wt.%, even more preferably more than 80 wt.%. most preferably more than 90 wt.% Fischer-Tropsch derived base oil. In an especially preferred embodiment not more than 5 wt.%, preferably not more than 2 wt.%, of the base oil is not a Fischer-Tropsch derived base oil. It is even more preferred that 100 wt% of the base oil is based on one or more Fischer-Tropsch derived base oils.

The total amount of base oil incorporated in the lubricating composition of the present invention is preferably in the range of from 60 to 99 wt.%, more preferably in the range of from 65 to 90 wt.% and most preferably in the range of from 70 to 85 wt.%, with respect to the total weight of the lubricating

composition .

Typically the base oil as used according to the present invention has a kinematic viscosity at 100°C (according to ASTM D445) of above 2.5 cSt and below 5.6 cSt . According to a preferred embodiment of the present invention the base oil has a kinematic viscosity at 100°C (according to ASTM D445) of between 3.5 and 4.5 cSt . In the event the base oil contains a blend of two or more base oils, it is preferred that the blend has a kinematic viscosity at 100°C of between 3.5 and 4.5 cSt .

Typically the lubricating compositions of the present invention would be utilised in, but not

necessarily limited to, SAE J300 viscosity grades OW-20, OW-30, OW-40, 5W-20, 5W-30 and 5W-40 as these are the grades which target fuel economy. As new SAE J300 viscosity grades are published, with lower viscosities than the current OW-20, the present invention would also be very much applicable to these new viscosity lower grades. It is conceivable that the present invention could also be used with higher viscosity grades.

The lubricating composition according to the present invention preferably has a Noack volatility (according to ASTM D 5800) of below 15 wt . % . Typically, the Noack volatility (according to ASTM D 5800) of the composition is between 1 and 15 wt.%, preferably below 14.6 wt . % and more preferably below 14.0 wt.%.

Preferably, the lubricating oil composition has a kinematic viscosity in the range of from 2 to 80 mm²/s at 100 °C, more preferably of from 3 to 70 mm²/s, most preferably of from 4 to 50 mm²/s.

The total amount of phosphorus in the lubricating oil composition herein is preferably less than or equal to 0.08 wt%, by weight of the lubricating composition.

The lubricating oil composition herein preferably has a sulphated ash content of not greater than 2.0 wt.%, more preferably not greater than 1.0 wt.% and most preferably not greater than 0.8 wt.%, based on the total weight of the lubricating oil composition. The lubricating oil composition herein preferably has a sulphur content of not greater than 1.2 wt.%, more preferably not greater than 0.8 wt.% and most preferably not greater than 0.2 wt.%, based on the total weight of the lubricating oil composition.

The lubricating composition according to the present invention further comprises one or more additives such as anti-oxidants, anti-wear additives, dispersants,

detergents, overbased detergents, extreme pressure additives, friction modifiers, viscosity index improvers, pour point depressants, metal passivators, corrosion inhibitors, demulsifiers , anti-foam agents, seal

compatibility agents and additive diluent base oils, etc.

As the person skilled in the art is familiar with the above and other additives, these are not further discussed here in detail. Specific examples of such additives are described in for example Kirk-Othmer

Encyclopedia of Chemical Technology, third edition, volume 14, pages 477-526.

Antioxidants that may be conveniently used include those selected from the group of aminic antioxidants and/or phenolic antioxidants.

In a preferred embodiment, said antioxidants are present in an amount in the range of from 0.1 to 5.0 wt . %, more preferably in an amount in the range of from

0.3 to 3.0 wt . %, and most preferably in an amount in the range of from 0.5 to 1.5 wt . %, based on the total weight of the lubricating oil composition.

Examples of aminic antioxidants which may be

conveniently used include alkylated diphenylamines, phenyl-a-naphthylamines, phenyl- -naphthylamines and alkylated a-naphthylamines . Preferred aminic antioxidants include

dialkyldiphenylamines such as p, p ' -dioctyl-diphenylamine, p, p ' -di-a-methylbenzyl-diphenylamine and N-p-butylphenyl- N-p ' -octylphenylamine, monoalkyldiphenylamines such as mono-t-butyldiphenylamine and mono-octyldiphenylamine, bis (dialkylphenyl) amines such as di-(2,4- diethylphenyl) amine and di (2-ethyl-4-nonylphenyl) amine, alkylphenyl-l-naphthylamines such as octylphenyl-1- naphthylamine and n-t-dodecylphenyl-l-naphthylamine, 1- naphthylamine, arylnaphthylamines such as phenyl-1- naphthylamine, phenyl-2-naphthylamine, N-hexylphenyl-2- naphthylamine and N-octylphenyl-2-naphthylamine,

phenylenediamines such as N, ' -diisopropyl-p- phenylenediamine and N, ' -diphenyl-p-phenylenediamine, and phenothiazines such as phenothiazine and 3,7- dioctylphenothiazine .

Preferred aminic antioxidants include those available under the following trade designations: "Sonoflex OD-3" (ex. Seiko Kagaku Co.), "Irganox L-57" (ex. Ciba

Specialty Chemicals Co.) and phenothiazine (ex. Hodogaya

Kagaku Co . ) .

Examples of phenolic antioxidants which may be conveniently used include C₇-C₉ branched alkyl esters of

3.5-bis (1, 1-dimethyl-ethyl ) -4-hydroxy-benzenepropanoic acid, 2-t-butylphenol, 2-t-butyl-4-methylphenol, 2-t- butyl-5-methylphenol, 2, 4-di-t-butylphenol, 2, 4-dimethyl- 6-t-butylphenol, 2-t-butyl-4-methoxyphenol, 3-t-butyl-4- methoxyphenol, 2, 5-di-t-butylhydroquinone, 2, 6-di-t-butyl- 4-alkylphenols such as 2, 6-di-t-butylphenol, 2,6-di-t- butyl-4-methylphenol and 2, 6-di-t-butyl-4-ethylphenol,

2.6-di-t-butyl-4-alkoxyphenols such as 2, 6-di-t-butyl-4- methoxyphenol and 2, 6-di-t-butyl-4-ethoxyphenol, 3,5-di-t- butyl-4-hydroxybenzylmercaptooctylacetate, alkyl-3- (3, 5- di-t-butyl-4-hydroxyphenyl) propionates such as n- octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, n- butyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate and 2'- ethylhexyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2 , 6-d-t-butyl-OC-dimethylamino-p-cresol, 2 , 2 ' -methylene- bis (4-alkyl-6-t-butylphenol) such as 2, 2 ' -methylenebis (4- methyl-6-t-butylphenol, and 2, 2-methylenebis (4-ethyl-6-t- butylphenol) , bisphenols such as 4 , 4 ' -butylidenebis ( 3- methyl-6-t-butylphenol, 4,4' -methylenebis (2, 6-di-t- butylphenol) , 4, 4 ' -bis (2, 6-di-t-butylphenol) , 2,2-(di-p- hydroxyphenyl) propane, 2, 2-bis (3, 5-di-t-butyl-4- hydroxyphenyl) propane, 4,4' -cyclohexylidenebis (2, 6-t- butylphenol) , hexamethyleneglycol-bis [3- (3, 5-di-t-butyl-4- hydroxyphenyl) propionate] , triethyleneglycolbis [3- (3-t- butyl-4-hydroxy-5-methylphenyl) propionate] , 2,2'-thio-

[diethyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate] , 3 , 9-bis { 1 , 1 -dimethyl-2- [3- ( 3 -t -buty1-4 -hydroxy-5-methyl- phenyl) propionyloxy ] ethyl } 2, 4, 8, 10- tetraoxaspiro [5,5] undecane, 4,4' -thiobis (3-methyl-6-t- butylphenol) and 2 , 2 ' -thiobis ( 4 , 6-di-t-butylresorcinol ) , polyphenols such as tetrakis [methylene-3- (3, 5-di-t-butyl- 4-hydroxyphenyl) propionate ] methane, 1,1, 3-tris (2-methyl-4- hydroxy-5-t-butylphenyl) butane, 1,3, 5-trimethyl-2 , 4, 6- tris (3, 5-di-t-butyl-4-hydroxybenzyl ) benzene, bis-[3,3'- bis (4 ' -hydroxy-3 ' -t-butylphenyl) butyric acid] glycol ester,

2- (3 ' , 5 ' -di-t-butyl-4-hydroxyphenyl)methyl-4- (2", 4"-di-t- butyl-3"-hydroxyphenyl)methyl-6-t-butylphenol and 2,6- bis (2 ' -hydroxy-3 ' -t-butyl-5 ' -methylbenzyl ) -4-methylphenol, and p-t-butylphenol - formaldehyde condensates and p-t- butylphenol - acetaldehyde condensates.

Preferred phenolic antioxidants include those available under the following trade designations: "Irganox L-135" (ex. Ciba Specialty Chemicals Co.), "Yoshinox SS" (ex. Yoshitomi Seiyaku Co.), "Antage W-400" (ex. Kawaguchi Kagaku Co.), "Antage W-500" (ex. Kawaguchi Kagaku Co.), "Antage W-300" (ex. Kawaguchi Kagaku Co.), "Irganox L109" (ex. Ciba Speciality Chemicals Co.), "Tominox 917" (ex. Yoshitomi Seiyaku Co.), "Irganox L115" (ex. Ciba

Speciality Chemicals Co.), "Sumilizer GA80" (ex. Sumitomo Kagaku), "Antage RC" (ex. Kawaguchi Kagaku Co.), "Irganox L101" (ex. Ciba Speciality Chemicals Co.), "Yoshinox 930" (ex. Yoshitomi Seiyaku Co.).

The lubricating oil composition of the present invention may comprise mixtures of one or more phenolic antioxidants with one or more aminic antioxidants.

Anti-wear additives that may be conveniently used include zinc-containing compounds such as zinc

dithiophosphate compounds selected from zinc dialkyl-, diaryl- and/or alkylaryl- dithiophosphates , molybdenum- containing compounds, boron-containing compounds and ashless anti-wear additives such as substituted or unsubstituted thiophosphoric acids, and salts thereof.

In a preferred embodiment, the lubricating oil composition may comprise a single zinc dithiophosphate or a combination of two or more zinc dithiophosphates as anti-wear additives, the or each zinc dithiophosphate being selected from zinc dialkyl-, diaryl- or alkylaryl- dithiophosphates .

Zinc dithiophosphate is a well known additive in the art and may be conveniently represented by general formula II;

s s wherein R^z to R may be the same or different and are each a primary alkyl group containing from 1 to 20 carbon atoms preferably from 3 to 12 carbon atoms, a secondary alkyl group containing from 3 to 20 carbon atoms, preferably from 3 to 12 carbon atoms, an aryl group or an aryl group substituted with an alkyl group, said alkyl substituent containing from 1 to 20 carbon atoms preferably 3 to 18 carbon atoms.

Zinc dithiophosphate compounds in which to are all different from each other can be used alone or in admixture with zinc dithiophosphate compounds in which R² to R⁵ are all the same.

Preferably, the or each zinc dithiophosphate used in the present invention is a zinc dialkyl dithiophosphate.

Examples of suitable zinc dithiophosphates which are commercially available include those available ex.

Lubrizol Corporation under the trade designations "Lz 1097" and "Lz 1395", those available ex. Chevron Oronite under the trade designations "OLOA 267" and "OLOA 269R", and that available ex. Afton Chemical under the trade designation "HITEC 7197"; zinc dithiophosphates such as those available ex. Lubrizol Corporation under the trade designations "Lz 677A", "Lz 1095" and "Lz 1371", that available ex. Chevron Oronite under the trade designation "OLOA 262" and that available ex. Afton Chemical under the trade designation "HITEC 7169"; and zinc

dithiophosphates such as those available ex. Lubrizol Corporation under the trade designations "Lz 1370" and "Lz 1373" and that available ex. Chevron Oronite under the trade designation "OLOA 260".

The lubricating oil composition herein may generally comprise in the range of from 0.4 to 1.2 wt . % of zinc dithiophosphate, based on total weight of the lubricating oil composition.

Examples of such molybdenum-containing compounds may conveniently include molybdenum dithiocarbamates , trinuclear molybdenum compounds, for example as described in WO1998026030, sulphides of molybdenum and molybdenum dithiophosphate .

Boron-containing compounds that may be conveniently used include borate esters, borated fatty amines, borated epoxides, alkali metal (or mixed alkali metal or alkaline earth metal) borates and borated overbased metal salts.

Typical detergents that may be used in the

lubricating composition herein include one or more salicylate and/or phenate and/or sulphonate detergents.

However, as metal organic and inorganic base salts which are used as detergents can contribute to the sulphated ash content of a lubricating oil composition, in a preferred embodiment of the present invention, the amounts of such additives are minimised.

Furthermore, in order to maintain a low sulphur level, salicylate detergents are preferred.

Thus, in a preferred embodiment, the lubricating oil composition herein may comprise one or more salicylate detergents .

In order to maintain the total sulphated ash content of the lubricating oil composition herein at a level of preferably not greater than 2.0 wt . %, more preferably at a level of not greater than 1.0 wt . % and most preferably at a level of not greater than 0.8 wt . %, based on the total weight of the lubricating oil composition, said detergents are preferably used in amounts in the range of

0.05 to 20.0 wt . %, more preferably from 1.0 to 10.0 wt . % and most preferably in the range of from 2.0 to 5.0 wt . %, based on the total weight of the lubricating oil composition .

Furthermore, it is preferred that said detergents, independently, have a TBN (total base number) value in the range of from 10 to 500 mg.KOH/g, more preferably in the range of from 30 to 350 mg.KOH/g and most preferably in the range of from 50 to 300 mg.KOH/g, as measured by ISO 3771.

The lubricating oil compositions herein may

additionally contain an ash-free dispersant which is preferably admixed in an amount in the range of from 5 to 15 wt . %, based on the total weight of the lubricating oil composition.

Examples of ash-free dispersants which may be used include the polyalkenyl succinimides and polyalkenyl succininic acid esters disclosed in Japanese Patent Nos . 1367796, 1667140, 1302811 and 1743435. Preferred

dispersants include borated succinimides.

Examples of viscosity index improvers which may conveniently be used in the lubricating composition herein include the styrene-butadiene stellate copolymers, styrene-isoprene stellate copolymers and the

polymethacrylate copolymer and ethylene-propylene copolymers (also known as olefin copolymers) of the crystalline and non-crystalline type. Dispersant- viscosity index improvers may be used in the lubricating composition herein. However, preferably the composition herein contains less than 1.0 wt.%, preferably less than 0.5 wt.%, of a Viscosity Index improver concentrate (i.e. VI improver plus "carrier oil" or "diluent"), based on the total weight of the composition. Most preferably, the composition is free of Viscosity Index improver

concentrate. The term "Viscosity Modifier" as used hereafter is meant to be the same as the above-mentioned term "Viscosity Index improver concentrate".

Preferably, the composition contains at least 0.1 wt . % of a pour point depressant. As an example, alkylated naphthalene and phenolic polymers, polymethacrylates, maleate/ fumarate copolymer esters may be conveniently used as effective pour point depressants. Preferably not more than 0.3 wt . % of the pour point depressant is used.

Furthermore, compounds such as alkenyl succinic acid or ester moieties thereof, benzotriazole-based compounds and thiodiazole-based compounds may be conveniently used in the lubricating composition herein as corrosion inhibitors .

Compounds such as polysiloxanes, dimethyl

polycyclohexane and polyacrylates may be conveniently used in the lubricating composition herein as defoaming agents.

Compounds which may be conveniently used in the lubricating composition herein as seal fix or seal compatibility agents include, for example, commercially available aromatic esters.

The above-mentioned additives are typically present in an amount in the range of from 0.01 to 35.0 wt.%, based on the total weight of the lubricating composition, preferably in an amount in the range of from 0.05 to 25.0 wt.%, more preferably from 1.0 to 20.0 wt.%, based on the total weight of the lubricating composition.

Preferably, the composition contains at least 9.0 wt.%, preferably at least 10.0 wt.%, more preferably at least 11.0 wt% of an additive package comprising an anti- wear additive, a metal detergent, an ashless dispersant and an anti-oxidant .

The lubricating compositions herein are preferably engines oils for use in the crankcase of an engine. The engine oil may include a heavy duty diesel engine oil, a passenger car motor engine oil, as well as other types of engine oils, such as motor cycle oils and marine engine oils .

The lubricating compositions herein may be so-called

"low SAPS" (SAPS = sulphated ash, phosphorus and

sulphur), "mid SAPS" or "regular SAPS" formulations.

For Passenger Car Motor Oil (PCMO) engine oils the above ranges mean:

- a sulphated ash content (according to ASTM D 874) of up to 0.5 wt.%, up to 0.8 wt . % and up to 1.5 wt.%, respectively;

a phosphorus content (according to ASTM D 5185) of up to 0.05 wt.%, up to 0.08 wt.% and typically up to 0.1 wt.%, respectively; and

a sulphur content (according to ASTM D 5185) of up to 0.2 wt.%, up to 0.3 wt.% and typically up to 0.5 wt.%, respectively.

For Heavy Duty Diesel Engine Oils the above ranges mean:

a sulphated ash content (according to ASTM D 874) of up to 1 wt.%, up to 1 wt.% and up to 2 wt.%,

respectively;

a phosphorus content (according to ASTM D 5185) of up to 0.08 wt.% (low SAPS) and up to 0.12 wt.% (mid

SAPS) , respectively; and

a sulphur content (according to ASTM D 5185) of up to 0.3 wt.% (low SAPS) and up to 0.4 wt.% (mid SAPS), respectively.

The lubricating compositions of the present

invention may be conveniently prepared using conventional formulation techniques by admixing base oil with the ashless friction modifier and other additive components/additive package at a temperature of, for example, around 60 °C.

It has surprisingly been found that the lubricating composition described herein provides reduced wear in the presence of soot, preferably at a level of soot in the range of from 1 wt% to 5 wt%, by weight of the

lubricating composition.

The present invention is described below with reference to the following Examples, which are not intended to limit the scope of the present invention in any way .

Example 1 and Comparative Example 1

Comparative Example 1 was a Heavy Duty Diesel Engine

Oil having the formulation shown in Table 1. Said formulations were manufactured by blending together the various components using conventional mixing techniques.

Example 1 is the same as Comparative Example 1 but top treated with 1 wt% "Additin M10229". Additin M10229 is an ashless friction modifier commercially available from RheinChemie .

Table 1

1. GTL 4 is a Fischer-Tropsch derived base oil having a kinematic viscosity at 100°C (ASTM D445) of approximately 4 est (mm²/s) . This GTL 4 base oil may be conveniently manufactured by the process described in e.g.

WO20020070631.

2. GTL8 is a Fischer-Tropsch derived base oil having a kinematic viscosity at 100°C (ASTM D445) of approximately 8 est (mm²/s) . This GTL 8 base oil may be conveniently manufactured by the process described in e.g.

WO2002070631.

3. Anti-rust additive commercially available from Chevron-Oronite .

4. VI Improver commercially available from Infineum.

5. HDDEO Additive package comprising salicylate detergent, high molecular weight dispersant, ZDTP, Aminic anti-oxidant and phenolic antioxidant.

SRV Wear and Friction Testing

Comparative Example 1 and Example 1 were subjected to wear testing using the Optimol SRV-4 friction and wear testing platform. A cylinder-on-flat geometry was used for testing using test specimens purchased from Optimol. The hardened steel cylinder was 11x15 mm (diameter x length) . A custom sample pan holder was manufactured to fit the steel disks (6.9 x 22 mm) . The sample pan holds approximately 2 ml of oil, and allows fully flooded extended duration lubricant testing to be conducted in the SRV. A special arrangement on the alignment pin slots allowed the pan to be positioned 5 mm to either the left or right in the SRV sample chamber (in addition to the centre position) . This allowed for up to three

independent tests (3 mm stroke) to be conducted on each side of the disk. The disk specimens were either steel or DLC-coated steel; the cylinder was always a steel surface. The two test specimens (e.g. cylinder and disk) were installed in the test chamber and pressed together with a specified normal force. The top specimen

oscillates on the bottom specimen. Frequency, stroke, test load, test temperature and test duration are pre^¬ set; friction force is continually measured. The friction coefficient is automatically calculated and recorded during the entire test duration. Wear volume is measured and recorded either during and/or after the test.

During testing of Comparative Example 1 and Example 1, 4.76 wt% of soot, by weight of the total lubricating composition, was present.

The following test conditions were used for the testing of Comparative Example 1 and Example 1:

Load: 200N

Stroke: 3 mm

Duration: 3 hours

Temperature: 130°C

The friction coefficient and wear volume

measurements for Comparative Example 1 and Example 1 are shown in Table 2 below.

Table 2

Examples 2-6 and Comparative Examples 1-3

Another set of experiments were conducted to demonstrate the effect of adding various amounts of Additin M10229 to a heavy duty diesel engine oil, in the presence and absence of soot .

The formulations that were tested are based on

Comparative Example 1, top treated with various amounts of carbon black (to simulate the presence of soot) and various amounts of Additin M10229, as shown in Table 3 below .

The wear volume for each of the formulations set out in Table 3 were measured using the same test method as used above for Example 1 and Comparative Example 1. The wear volume measurements are shown in Table 3 below .

Table 3

Discussion

Table 2 shows that addition of 1 wt% of Additin M10229 to a lubricating composition leads to a reduction in both friction coefficient and wear volume. Additin M10229 is marketed as an organic friction modifier, so the additional wear reduction is significant and

unexpected.

Since Additin M10229 does not contain phosphorus it can be used in addition to a ZDTP anti-wear additive.

Table 3 shows the addition of various concentrations of Additin M10229 to a lubricating composition leads to a reduction in wear volume. This benefit is seen in the presence and absence of soot (carbon black) .

Claims

C L A I M S

1. Use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂4 fatty acid and Ci₂-C₂4 fatty amine for providing reduced wear .

2. Use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂₄ fatty acid and Ci₂-C₂₄ fatty amine for providing reduced friction and reduced wear.

3. Use according to Claim 1 or 2 wherein the Ci₂-C₂₄ fatty acid present in the ashless friction modifier is a

Ci4-C₂₂ fatty acid.

4. Use according to any of Claims 1 to 3 wherein the Ci₂-C₂₄ fatty acid present in the ashless friction modifier is a Ci₆-C₂₀ fatty acid.

5. Use according to Claims 1 to 4 wherein the Ci₂-C₂₄ fatty acid present in the ashless friction modifier is a Ci8 fatty acid.

6. Use according to Claims 1 to 5 wherein the Ci₂-C₂ fatty amine in the ashless friction modifier is a C_i4-C₂₂ fatty amine.

7. Use according to Claims 1 to 6 wherein the Ci₂-C₂ fatty amine in the ashless friction modifier is a Ci₆-C₂₀ fatty amine.

8. Use according to Claims 1 to 7 wherein the Ci₂-C₂ fatty amine in the ashless friction modifier is a Ci₈ fatty amine.

9. Use according to Claim 1 to 8 wherein the ashless friction modifier additionally comprises Ci₂-C₂ fatty amide .

10. Use according to any of Claims 1 to 9 wherein the lubricating composition comprises from 0.05 wt% to 3 wt% of ashless friction modifier, by weight of the

lubricating composition.

11. Use according to any of Claims 1 to 10 wherein the base oil comprises a Fischer-Tropsch derived base oil.

12. Use of a lubricating composition comprising (i) base oil and (ii) ashless friction modifier comprising Ci₂-C₂4 fatty acid and Ci₂-C₂4 fatty amine for providing reduced wear in the presence of soot .

13. Use according to Claim 12 wherein the soot is present at a level of from 1 wt% to 5 wt%, by weight of the lubricating composition.

14. Use according to any of Claims 1 to 13 wherein the lubricating composition comprises less than or equal to 0.08 wt% of phosphorus, by weight of the lubricating composition .

15. Use according to any of Claims 1 to 14 wherein the lubricating composition is a passenger car motor oil.

16. Use according to any of Claims 1 to 14 wherein the lubricating composition is a heavy duty diesel engine oil .