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)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 C5 to C12, and about 20 to 70 molar % of at least one branched acid having a carbon number in the range between about C5 to C10 and wherein no more than 10% of the branched acids used to form the biodegradable synthetic ester base stock contains a quaternary carbon; 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 DEG C.; a viscosity of less than 7500 cps at -25 DEG C.; and oxidative stability of up to 45 minutes as measured by HPDSC.