Evaluation of High Performance Two-Stroke Cycle Engine Lubricants

The two-stroke cycle engine offers unique operational characteristics which make it attractive for use over a wide range of power applications. Confusion experienced by consumers regarding the choice of an appropriate lubricant for a particular application has led to widespread recommendations for lubricants which meet the solitary industrywide performance specification, BIA TC-W. Concerns that this universal usage of an outboard motor lubricant specification might lead to product misapplications initiated the development of a lubricant classification system for all types of two-stroke cycle engines.

SAE, ASTM and CEC have jointly proposed a four-category classification system for industry approval. Despite the apparent suitability of the system for identifying satisfactory and inferior quality two-stroke cycle engine lubricants, some engine manufacturers and extremely quality conscious consumers desire supplemental test procedures for identifying superior quality lubricants. This paper describes some appropriate supplemental test procedures. Also, a new performance rating system for piston ring sticking is introduced, and its use is described in standard industry tests as well as the supplemental test procedures.