Patent ID: 7166562

Claim:
A method for enhancing the life of gas engine oils as evidenced by a reduction in at least one of viscosity increase, oxidation, nitration, TAN increase, and TBN depletion of the gas engine oil during use comprising formulating a gas engine oil comprisinig a base stock having a viscosity at 100° C. of from 9 to 13 cSt, the base stock being a synthetic, hydrocracked or solvent refined oil or mixture thereof a minor amount of an anti oxidant in the range of about 0.1 to 2 vol %, from about 0.2 to about 0.5 vol % of antiwear additives, and an amount of a viscosity index improver not sufficient to produce a multi-grade gas engine oil lubricating composition, the amount used being in the range of about 0.1 to 3 vol % which gas engine oil lubricating composition does not contain aminic anti oxidants and wherein the anti oxidant is selected from the group consisting of phenolic anti oxidants, and a minor amount of a low ash gas engine oil detergent system having a TBN of about 50 to about 300 wherein the gas engine oil has a low ash content in the range of 0.1 to 0.6 wt % and wherein the life of said as engine oil is enhanced in comparison to gas engine oils which do not contain both phenolic anti oxidant(s) and viscosity index improver(s).