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New emission requirements (PZEV and ULEV) have sparked interest in further improvement in engine oil consumption. This paper reviews measurement equipment and parameters currently used to describe bore finish, as well as recent research on bore finish effects on oil consumption. Typical bore finishes in use are benchmarked for a number of engines, and recommendations are presented for future finishes. The paper closes with some case histories illustrating bore finish effects on oil consumption and current problems in this area.

Past oil consumption reduction efforts were motivated by operating cost, petroleum conservation, or customer quality perception concerns. Recent efforts have been driven by exhaust catalyst poisoning considerations. The need to certify emissions to a higher mileage level and optimization efforts on the emission control systems have resulted in higher objectives for oil control. This paper focuses on one important factor in the control of lubrication oil consumption in internal combustion engines. Previous studies have related bore finish to oil consumption through either theoretical or experimental techniques. In this study, a mathematical model is derived statistically from experimental data utilizing regression analysis and a new transient radiotracer oil consumption measurement technique. The model predicts oil consumption levels expected with variations in cylinder bore finish, and suggests the important surface finish parameters to specify and control for minimum oil consumption.