The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a core portion and three or more arm portions, wherein each of the arm portions consists of a polymer chain comprising a structural unit represented by the following formula (1), and one end of the polymer chain is bonded to the core portion, and wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less. ##STR00001## [R.sup.1 represents hydrogen or a methyl group, and R.sup.2 represents a C1 to C36 alkyl group.]

A method for improving corrosion protection and friction coefficient in an engine or other mechanical component lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition comprising a lubricating oil base stock as a major component, and a mixture of (i) at least one organic molybdenum compound, and (ii) at least one borated ester, as a minor component. Corrosion protection and friction coefficient are improved as compared to corrosion protection and friction coefficient achieved using a lubricating oil containing a minor component other than the mixture of (i) at least one organic molybdenum compound, and (ii) at least one borated ester.

A method for improving corrosion protection and friction coefficient in an engine or other mechanical component lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition comprising a lubricating oil base stock as a major component, and a mixture of (i) at least one organic molybdenum compound, and (ii) at least one borated ester, as a minor component. Corrosion protection and friction coefficient are improved as compared to corrosion protection and friction coefficient achieved using a lubricating oil containing a minor component other than the mixture of (i) at least one organic molybdenum compound, and (ii) at least one borated ester.

The invention provides a lubricating composition containing an aromatic compound and an oil of lubricating viscosity. The invention further relates to the use of the lubricating composition in an internal combustion engine. The invention further relates to the use of the aromatic compound as an antiwear agent.

The invention provides a lubricating composition containing an aromatic compound and an oil of lubricating viscosity. The invention further relates to the use of the lubricating composition in an internal combustion engine. The invention further relates to the use of the aromatic compound as an antiwear agent.

A lubricating composition for use in the crankcase of an engine comprising (i) a base oil; (ii) one or more organo-molybdenum compounds at a level sufficient to provide from 100 to 1000 ppmw of molybdenum; and (iii) from 0.2 wt % to 5.0 wt %, by weight of the lubricating composition, of one or more organic polymeric friction reducing additives, wherein the one or more organic polymeric friction reducing additives has a molecular weight ranging from 1000 to 30000 Daltons and is the reaction product of: a) a hydrophobic polymeric sub unit which comprises a hydrophobic polymer selected from polyolefins, polyacrylics and polystyrenyls; b) a hydrophilic polymeric sub unit which comprises a hydrophilic polymer selected from polyethers, polyesters, polyamides; c) optionally at least one backbone moiety capable of linking together polymeric sub units; and d) optionally a chain terminating group. The lubricating composition provides improvements in terms of reduced friction and wear, in addition to improved fuel economy performance.

A lubricating composition for use in the crankcase of an engine comprising (i) a base oil; (ii) one or more organo-molybdenum compounds at a level sufficient to provide from 100 to 1000 ppmw of molybdenum; and (iii) from 0.2 wt % to 5.0 wt %, by weight of the lubricating composition, of one or more organic polymeric friction reducing additives, wherein the one or more organic polymeric friction reducing additives has a molecular weight ranging from 1000 to 30000 Daltons and is the reaction product of: a) a hydrophobic polymeric sub unit which comprises a hydrophobic polymer selected from polyolefins, polyacrylics and polystyrenyls; b) a hydrophilic polymeric sub unit which comprises a hydrophilic polymer selected from polyethers, polyesters, polyamides; c) optionally at least one backbone moiety capable of linking together polymeric sub units; and d) optionally a chain terminating group. The lubricating composition provides improvements in terms of reduced friction and wear, in addition to improved fuel economy performance.

A lubricating composition includes an oil of lubricating viscosity and an oil-soluble dispersant viscosity modifier. The dispersant viscosity modifier includes an olefin-based polymer backbone and at least one pendent group derived from a functionalized aliphatic amine. Each pendent group is independently attached to the olefin-based polymer backbone. The pendent group is non-ionic, non-basic, and non-acidic and includes a functional group which includes at least one heteroatom other than nitrogen.

The use of polyalkylenyl succinic anhydrides to stabilize an additive concentrate which includes a salicylate detergent and a nitrogen-free ashless organic friction modifier.

The invention provides a method of lubricating a compression-ignition internal combustion engine with a maximum laden mass over 2,700 kg comprising supplying to the engine a lubricating composition comprising: an oil of lubricating viscosity, a 300 TBN or higher alkaline earth metal sulphonate detergent having a metal ratio of 10 to 40, 0.1 wt % to 4 wt % of a borated polyisobutylene succinimide dispersant, wherein the polyisobutylene from which the borated polyisobutylene succinimide is derived has a number average molecular weight of 550 to 1150, and 0.1 wt % to 6 wt % of a polyisobutylene succinimide, wherein the polyisobutylene from which polyisobutylene succinimide is derived has a number average molecular weight of 1550 to 2500, 0 wt % to 0.2 wt % of a phenolic based detergent, wherein the total amount of soap delivered by the alkaline earth metal sulphonates (typically calcium sulphonate) is 0.4 to 1 wt % of the lubricating composition, and wherein the lubricating composition has a sulphated ash content of not more than 1.5 wt %.