Patent ID: 7790660

Claim:
A lubricant composition suitable for use in gearboxes comprising: a major amount of a base oil consisting of polyalkylene glycol fluid or a mixture of polyalkylene glycol fluids, and based on the total weight of the composition; (a) from 0.1 to 1.0 wt % of an rust inhibitor composition consisting of: (i) a N-acylsarcosine of the formula where R is an alkyl or alkenyl group of from about 10 to about 30 carbon atoms; and (ii) an imidizole of the formula where R 1 is an alkyl or alkenyl group of from about 10 to about 30 carbon atoms and R 2 is a hydroxy alkyl group of from about 1 to about 6 carbon atoms; and (b) from 0.1 to 2.0 wt % of a antioxidant consisting of: (iii) an alkylated diphenyl amine of the formula where R 3 and R 4 are independently alkyl groups of from about 2 to about 20 carbon atoms; and (iv) a hindered phenol of the formula where R 5 and R 6 are independently alkyl groups of from about 3 to 9 carbon atoms, x is an integer of from 1 to about 4, and y is an integer of from about 1 to about 4; (c) a silicon defoamant.