A lubricating oil composition comprising (A) an oil of lubricating viscosity in a major amount; and, (B) as an additive component in a minor amount, an oil-soluble zinc salt of a dithiophosphoric acid, the dithiophosphoric acid being the reaction product of phosphorus pentasulphide with a mixture of at least one first alcohol of the formula ROH where R is an aliphatic hydrocarbyl group having at least four carbon atoms or is an alkaryl group, and at least one second alcohol which is an ester of a polyhydric alcohol.