Method and Composition for Preventing or Reducing Engine Knock and Pre-ignition in High Compression Spark Ignition Engines

A method for preventing or reducing engine knock or pre-ignition in a high compression spark ignition engine lubricated with a lubricating oil by introducing to a combustion chamber of the engine from 0.1 to 5% by volume of the gasoline used a lubricating oil as a formulated oil, said formulated oil having a composition comprising (i) a major amount of a lubricating oil base stock comprising at least 80% by weight of one branched ester having at least 15% of the total carbons in the form of methyl groups, and (ii) a minor amount of at least one ashless amine phosphate antiwear additive. Also provided is a lubricating engine oil for high compression spark ignition engines including (i) a major amount of a lubricating oil base stock comprising at least 80% by weight a trimethylol propane ester of 50:50 mixture of isobutyric acid and 3,5,5-trimethylhexanoic acid and (ii) a minor amount of at least one amine phosphate ashless antiwear additive.