Abstract: A biodegradable lubricant which is prepared from: about 60-99% by weight of at least one biodegradable synthetic ester base stock which comprises the reaction product of: a branched or linear alcohol having the general formula R(OH).sub.n, wherein R is an aliphatic or cyclo-aliphatic group having from about 2 to 20 carbon atoms and n is at least 2; and mixed acids comprising about 30 to 80 molar % of a linear acid having a carbon number in the range between about C.sub.5 to C.sub.12, and about 20 to 70 molar % of at least one branched acid having a carbon number number in the range between about C.sub.5 to C.sub.13 ; wherein the ester base stock exhibits the following properties: at least 60% biodegradation in 28 days as measured by the Modified Sturm test; a pour point of less than -25.degree. C; and a viscosity of less than 7500 cps at -25.degree. C; about 1 to 20% by weight lubricant additive package; and about 0 to 20% of a solvent.