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Reduced vehicle oil consumption is desired to conserve petroleum resources, lower vehicle operating cost, decrease exhaust hydrocarbon levels, increase catalyst life, and enhance the customer's perception of vehicle quality. To effectively accomplish this and provide optimum remedial measures, it is necessary to know the relative contribution of each of the three systems consuming oil. The systems of interest are the power cylinder system, the engine overhead system, and the PCV system. Controlling factors and evaluation techniques are discussed for each system individually, and test results showing the relative contribution of each system are presented.

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.

To reduce parasitic losses, a project was initiated to design, develop and bring to production a piston ring set which reduces engine friction while maintaining ring performance. In this paper, theoretical considerations affecting piston ring friction, and their implication in ring design, are discussed. An estimate of friction reduction and fuel economy improvement which can be achieved is calculated. Features of the resulting designs are reviewed, and friction, dynamometer, and vehicle test results are presented. Future ring design changes for reduced friction are reviewed.