LUBRICANT COMPOSITIONS COMPRISING A DISPERSANT, A TRINUCLEAR MOLYBDENUM COMPOUND AND A DIFFERENT ANTIOXIDANT

A diesel engine lubricant composition comprising a base stock, a dispersant and an antioxidant comprising an oil soluble trinuclear organomolybdenum compound of the generic formula: Mo3Sx-(Q) (I) wherein x is from 4 to 10 and Q is a core is a core group, which may be a ligand, and at least one other compound selected from a phenolic and an aminic compound. The composition is capable of controlling the viscosity of the lubricant in the presence of soot and to retain the dispersancy of the dispersant. The compositions of the present invention minimise wear in engines and undesirable emission from exhaust caused by incomplete combustion from vehicles which use diesel engines and lubricants therefor. The combination of antioxidants perform better at controlling soot induced viscosity increase than the individual compounds.