Abstract: A lubricant composition is described, particularly for engine oils, comprising a base oil of viscosity from 3 to 26 cSt (mm2/s) at 100° C. and an antiwear additive combination comprising (a) an oil soluble or oil dispersible phosphorus-free organo-molybdenum compound, (b) an ashless, sulfur-containing organo-phosphorus compound, and optionally (c) a zinc thiophosphate compound selected from one or more of zinc dialkyldithiophosphate, zinc diaiyldithiophosphate, zinc alkylaiyldithiophosphate and zinc arylalkyldithiophosphate. The molybdenum compound may be a carbamate, e.g., MoDTC but is preferably nitrogen-free, e.g., a carboxylate.

Abstract: Foaming of a lube oil comprising a base stock derived from wax isomeration and an additive package is effectively reduced to within specification limits of 50 ml/ml over a temperature range of from at least 24.degree. C. to 93.5.degree. C. by adding to the oil an effective amount of an antifoamant exhibiting a spreading coefficient of at least about 2 mN/m. This has been found to be particularly effective in reducing foaming of lube oils containing a mixture of a wax isomerate oil and a petroleum oil fraction. Antifoamants typically used with conventional lube oils containing one or more petroleum fraction base stocks, but which do not exhibit a spreading coefficient of at least 2 mN/m with the wax isomerate containing oil, have been found not to be effective in reducing the foaming of the oil.