An additive package for an internal combustion engine crankcase lubricating oil composition, which additive package comprises or is made by admixing: a diluent oil of lubricating viscosity; and the following additives: a polymeric friction modifier present on an active matter basis in an amount of at least 0.1 mass%, based on the mass of the additive package, the majority of molecules of the polymeric friction modifier having a molecular weight of from 1,000 to 30,000 Da, and wherein the polymeric friction modifier is the reaction product of: (a) a functionalised polyolefin which is functionalised with a diacid or anhydride functional group; (b) a polyether having a molecular weight in the range of 300 to 5,000 Daltons; (c) a polyol; and, (d) a monocarboxylic acid chain terminating group an ashless organic friction modifier which is glycerol mono-oleate, present on an active matter basis in an amount of from at least 0.5 mass % to less than 10 mass %, based on the mass of the additive package; and, wherein the additive package does not have a total base number as measured by ASTM D2896 of between 62 and 63.5. a diluent oil of lubricating viscosity; and the following additives: a polymeric friction modifier present on an active matter basis in an amount of at least 0.1 mass%, based on the mass of the additive package, the majority of molecules of the polymeric friction modifier having a molecular weight of from 1,000 to 30,000 Da, and wherein the polymeric friction modifier is the reaction product of: (a) a functionalised polyolefin which is functionalised with a diacid or anhydride functional group; (b) a polyether having a molecular weight in the range of 300 to 5,000 Daltons; (c) a polyol; and, (d) a monocarboxylic acid chain terminating group an ashless organic friction modifier which is glycerol mono-oleate, present on an active matter basis in an amount of from at least 0.5 mass % to less than 10 mass %, based on the mass of the additive package; and, wherein the additive package does not have a total base number as measured by ASTM D2896 of between 62 and 63.5. a polymeric friction modifier present on an active matter basis in an amount of at least 0.1 mass%, based on the mass of the additive package, the majority of molecules of the polymeric friction modifier having a molecular weight of from 1,000 to 30,000 Da, and wherein the polymeric friction modifier is the reaction product of: (a) a functionalised polyolefin which is functionalised with a diacid or anhydride functional group; (b) a polyether having a molecular weight in the range of 300 to 5,000 Daltons; (c) a polyol; and, (d) a monocarboxylic acid chain terminating group (a) a functionalised polyolefin which is functionalised with a diacid or anhydride functional group; (b) a polyether having a molecular weight in the range of 300 to 5,000 Daltons; (c) a polyol; and, (d) a monocarboxylic acid chain terminating group an ashless organic friction modifier which is glycerol mono-oleate, present on an active matter basis in an amount of from at least 0.5 mass % to less than 10 mass %, based on the mass of the additive package; and, wherein the additive package does not have a total base number as measured by ASTM D2896 of between 62 and 63.5.