Lubricating oil compositions

摘要

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 phosphorous content of less than or equal to 0.12 mass % as determined by ASTM D5185, which lubricating oil composition comprises or is made by admixing: an oil of lubricating viscosity, in a major amount; an oil-soluble or oil-dispersible polymeric friction modifier as an additive in an effective minor amount; and, an oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate metal salt as an additive in an effective minor amount. The polymeric friction modifier is a reaction product of solely (i) one or more polyalkylenes functionalized with at least one diacid or anhydride functional group and where the polyalkylene has a carbon chain length of 50-500 carbon atoms, (ii) one or more polyalkylene glycols, (iii) one or more polyols and (iv) one or more polycarboxylic acids with a C2 to C30 hydrocarbyl group.