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.

Abstract: A combination of a fluorosilicone antifoamant and a polyacrylate antifoamant have been found to be effective in reducing foaming of lubricating oils at both low and high temperatures and without degrading the air release time to the extent that would occur with a conventional silicone antifoamant. Neither type of antifoamant is effective in reducing foaming at both low and high temperatures by itself.