Patent ID: 8470752

Claim:
A method of lubricating an automotive engine using a lubricant composition comprising: (A) a Group III base stock as a major component, having a viscosity at 100° C. of 3 to 10 mm 2 /s, a viscosity index of at least 120, and a Noack evaporation loss of less than 20%; (B) 0.1-2% of a partial polyol ester friction reducing additive derived from the reaction of either glycerol or trimethylolpropane with a monocarboxylic acid of formula R 1 COOH, where R 1 is a straight or branched chain C 12 -C 18 aliphatic hydrocarbon group, the monocarboxylic acid having an iodine value of not more than 20 and a cloud point of not more than 45° C.; and (C) a saturated primary amide friction reducing additive of formula R 2 CONH 2 where R 2 is a straight or branched chain C 12 -C 18 aliphatic hydrocarbon group, wherein the ratio of the partial polyol ester to the saturated primary amide ranges from 60:40 wt. % to 40:60 wt. %; wherein the oxidative induction time of the friction reducing additive in (B), together with the friction reducing additive in (C), is at least 25 minutes, said oxidative induction time being measured using a high pressure differential scanning calorimeter after carrying out the steps comprising placing 5 mg of the friction reducing additive with 0.5% by weight of a phenolic antioxidant having a thioether group relative to the friction reducing additive in a 40 μl aluminium crucible and heating the calorimeter from 30° C. to 170° C. at a rate of 50° C./min followed by maintenance of the temperature at 170° C. with an air pressure of 40 bar and air flow of 50 ml/min.