A composition is disclosed which is directed to an oxidatively stable environmentally friendly lubricant base fluid comprising (A) at least one sulfurized triglyceride oil and (B) at least one oxidation inhibitor selected from the group consisting of (1) an alkyl phenol of the formula ##STR1## wherein R.sup.4 is an alkyl group containing from 1 up to 24 carbon atoms, R.sup.5 is hydrogen, an alkyl group containing 1 or 2 carbon atoms or R.sup.4, and a is an integer of from 1 up to 4; (2) an ether of the formula ##STR2## wherein R.sup.6 is an alkyl group containing from 1 up to 12 carbon atoms, R.sup.4 is an alkyl group containing from 1 up to 24 carbon atoms and b is an integer of from 1 up to 5; and (3) at least one aromatic amine of the formula ##STR3## wherein R.sup.7 is ##STR4## and R.sup.8 and R.sup.9 are independently a hydrogen or an alkyl group containing from 1 up to 23 carbon atoms.