Patent ID: 8691738

Claim:
An aviation piston engine oil comprising (i) a base oil comprising: (a) from about 30.27 to 56.95 wt % based on the total weight of the base oil of one or more GTL base stock(s) and/or base oil(s), having a kinematic viscosity at 100° C. in the range of about 10 to 14 mm 2 /s; (b) about 30 wt % based on the total weight of the base oil of Bright Stock; (c) about zero to 26.6 wt % based on the total weight of the base oil of polyalpha olefin having a kinematic viscosity at 100° C. of about 6 mm 2 /s; and (d) with the proviso that the base oil is essentially free of Solvent Paraffinic Neutral (SPN) 600 mineral oil; (ii) about 11 wt % of additive comprising one or more of viscosity index improver, anti-oxidant, anti-foam agent, dye, ashless dispersant, extreme pressure additive; (iii) both an anti-wear additive and an anti-corrosion additive in the weight ratio of from about 30:1, wherein the anti-wear additive comprises tricresyl phosphate at about 1.50 wt. % based on the total weight of the engine oil and wherein the anti-corrosion additive comprises tolytriazole at about 0.05 wt. % based on the total weight of the engine oil; and (iv) wherein said oil is formulated with additives to meet SAE-J 1966 and SAE-J 1899 specifications for nondispersant and ashless dispersant oils respectively, and wherein the humidity cabinet rust test rating (ASTM D 1748 at 120° F., 100% relative humidity for 72 hours) of said oil is about 0.5 or less.