Abstract: An internal combustion engine crankcase lubricating oil composition having a sulphated ash content of no greater than 1.2 mass %, based on the mass of the lubricating oil composition, and a phosphorous content of no greater than 0.1 mass %, based on the mass of the lubricating oil composition, which lubricating oil composition comprises or is made by admixing: (A) a crankcase base oil of lubricating viscosity, in a major amount; and (B) the following additives, in respective minor amounts: (B1) a polymeric friction modifier being the reaction product of (a) a functionalised polyolefin, (b) a polyether, (c) a polyol, and (d) a monocarboxylic acid chain terminating group; and (B2) at least one oil-soluble molybdenum compound.