Two-stroke-cycle gasoline engines are generally more prone to preignition than are four-stroke-cycle engines due to the absence of the internal cooling that takes place during the induction stroke of the four-stroke-cycle engines. Preignition can lead to major piston damage, either directly due to localized overheating or as the result of preignition-induced detonation. Some lubricant additives that are widely used in four-stroke-cycle gasoline engine oils are known to increase the probability of preignition in gasoline two-stroke-cycle engines. This procedure is used to determine the tendency of an oil to induce preignition in both water-cooled and air-cooled two-stroke-cycle gasoline engines.

1.1 This test method evaluates the performance of lubricants intended for use in two-stroke-cycle spark-ignition gasoline engines which are prone to preignition.

1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

1.3 The values stated in SI units are the standard. The values given in parentheses are provided for information only.