Lubricating oil compositions comprising a trinuclear compound antioxidant

This invention relates to a lubricating oil composition comprising a Group I basestock and an antioxidant comprising an oil soluble trinuclear organomolybdenum compound of the generic formula (1): Mo3Sx-(Q) wherein x is from 4 to 10 and Q is a core group, which may be a ligand, wherein the basestock has a kinematic viscosity at 100° C. (KV100) from about 2 cSt to 50 cSt (2x10to 50x10m /sec), a saturates content of 10% w/w and a sulphur content of >0.03% w/w. The composition has an improved stability when compared with either a Group II, III or IV basestock containing the same antioxidant or a Group I basestock containing a dinuclear molybdenum dithiocarbamate.