This invention relates to a lubricating oil composition comprising a base stock and an antioxidant comprising an oil soluble trinuclear organomolybdenum compound of the generic formula: Mo3Sx—(Q) (1) wherein x is from 4 to 10 and Q is a core group, which may be a ligand, and at least one other compound selected from a phenolic and an aminic compound wherein the basestock has a kinematic viscosity at 100° C. (KV100) from about 2 cSt to 20 cSt (2×10−6 to 20×10−6 m2/sec) and a saturates content of at least 85%. The composition has a high oxidation stability, reduced deposit formation and is capable of giving rise to good fuel economy improvement.