A synthetic ester composition which exhibits thermal and oxidative stability, lower friction coefficient and lower wear, wherein the ester composition comprises the reaction product of: a branched or linear alcohol having the general formula R(OH)m, wherein R is an aliphatic or cyclo-aliphatic group having from about 2 to 20 carbon atoms and n is at least 2; and at least one branched mono-carboxylic acid which has a carbon number in the range between about C5 to C13; wherein the synthetic ester composition has between about 5-35% unconverted hydroxyl groups, based on the total amount of hydroxyl groups in the branched or linear alcohol.