The present invention provides an additive concentrate for use in forming a lubricating oil composition, the additive concentrate consisting of a diluent oil of lubricating viscosity present in a minor amount of less than 50 mass %, and a plurality of oil-soluble or oil-dispersible additives contained therein, wherein the combined amount of all of said plurality of additives in the additive concentrate is greater than 50 mass % on an active ingredient basis, and wherein the plurality of additives include the following additives: (A) one or more oil-soluble or oil-dispersible alkali metal or alkaline earth metal salicylate detergent(s) present in an amount of greater than or equal to 3.0 mass % on an active ingredient basis; (B) one or more oil-soluble or oil-dispersible ashless nitrogen-free organic friction modifier(s) which is one or more aliphatic (C7 to C29)hydrocarbyl fatty acid ester(s) present in an amount of greater than or equal to 0.50 mass % on an active ingredient basis; and (C) one or more oil-soluble or oil-dispersible poly(C2 to C6)alkylenyl succinic anhydride(s) present in an effective amount to stabilise the additive concentrate, wherein the number average molecular weight (Mn) of the poly(C2 to C6)alkylenyl chain(s) of the one or more poly(C2 to C6)alkylenyl succinic anhydride(s) is greater than or equal to 1250 daltons. The invention further relates to use of the alkylenyl succinic anhydride as an additive in the concentrate for improving the stablity of the additive concentrate and/or stabilizing the additive concentrate.