Gear fluids

A gear fluid composition for extreme pressure applications. The composition includes a base oil component and a friction modifier mixture. The mixture is provided by an alkyl phosphonic acid diester of the formula: wherein R 1 is a hydrocarbyl group containing from about 8 to about 24 carbon atoms, R 2 and R 3 are selected from a hydrocarbyl group containing from about 1 to about 8 carbon atoms, an alkyl phosphonic acid monoester of the formula wherein R 4 is a hydrocarbyl group containing from about 8 to about 24 carbon atoms, R 5 is hydrogen or hydrocarbyl group containing from about 1 to about 8 carbon atoms, and an amine salt of a partial ester of phosphoric acid represented by the formula wherein each of R 6 and R 8 is a hydrocarbyl group, and R 7 is hydrogen or a hydrocarbyl group, and wherein the ratio of (i) to (ii) ranges from about 3 to about 5.5.