Patent ID: 7683017

Claim:
A composition comprising a lubricating oil and an oil soluble synergistic mixture of antioxidants, said mixture comprising: a) from 0.1 to 10 weight percent of a first antioxidant according to formula I: wherein R 1 is selected from the group consisting of alkyl from 3 to 24 carbon atoms, —NHR, —NRR where R is independently selected alkyl from 1 to 18 carbon atoms; R 2 is hydrogen or alkyl from 1 to 20 carbon atoms; and b) from 0.1 to 5 weight percent of a second antioxidant selected from the formula wherein R 3 and R 4 are each independently hydrogen or alkyl from 1 to 20 carbon atoms; n is an integer from 1 to 3; R 5 is selected from the group consisting of branched and straight chain hydrocarbyl radicals having from 3 to 24 carbon atoms selected from alkyl, alkoxy, aralkyl or alkaryl, or —NHR 6 , —NR 6 R 7 where R 6 and R 7 are independently selected alkyl from 1 to 18 carbon atoms, or when R 4 is positioned adjacent to R 5 then R 6 together with R 4 can form a live- or six-membered heterocyclic ring.