A lubricant additive having antiwear and antioxidant properties is the reaction product of a sulfur-containing carboxylic acid and an etheramine, preferably 3,3'-thiodipropionic acid and N-isoeicosyloxypropyl-1,3-diaminopropane which is post reacted with an aliphatic alcohol, preferably oleyl alcohol, an aliphatic amine, preferably a tert-C.sub.12 to C.sub.14 amine and/or a trialkyl phosphite, preferably a tributylphosphite. The post-reaction product contains at least one ester, amide and/or phosphonate functional group.