Patent ID: 6872693

Claim:
A gear oil or transmission fluid composition comprising a major amount of a lubricant basestock and at least one functional additive wherein the lubricant basestock comprises a major amount of a mineral oil having a viscosity index of 120 or more, an iodine number of less than 9, a sulphur content of 0.004% by weight to less than 0.5% by weight, and comprising about 95% to 100% by weight saturates wherein at least about 55% of the saturates are aliphatic saturates and at least one polymer wherein the polymer is selected from the group consisting of an ethylene-alpha olefin copolymer, an ethylene-propylene polymer, an alpha olefin-unsaturated carboxylic reagent copolymer, and mixtures thereof; and the functional additive comprises a sulfurized olefin, or a salt derived from ammonia or an amine and phosphorus acid ester, or a mixture thereof.