An additive package for an internal combustion engine crankcase lubricating oil composition, which additive package comprises or is made by admixing: (A) 5-99.4 mass % based on the mass of the additive package, of a diluent oil of lubricating viscosity; and (B) the following additives: (B1) 0.1-10 mass % of a polymeric friction modifier, on an active matter basis, based on the mass of the additive package, which polymeric friction modifier is the reaction product of (a) a functionalised polyolefin, (b) a polyether, (c) a polyol, and (d) a monocarboxylic acid chain terminating group (B2) 0.5 to 10 mass % on an active matter basis, based on the mass of the additive package of one or more ashless organic friction modifiers that include a polar terminal group covalently bonded to a monomeric oleophilic hydrocarbon chain.