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An on-line oil consumption measurement system using the SO2 tracer method has characterized automotive gasoline engine oil consumption under various engine operating conditions, including a 200-hour durability test. An oil consumption map of total engine, individual cylinder, and valve train was produced for various speed and load ranges under both steady-state and step-transient operating conditions. The effect of spark timing as an additional engine parameter on the oil consumption was also investigated. Oil consumption maps have enlightened the conventional understanding of oil consumption characteristics and broadened the areas of concern for control technologies. This paper reports the benefit of the on-line oil consumption measurement system, the result of oil consumption history over the durability test, discrete measurement of oil consumption contribution within the engine, and various oil consumption characteristics affected by engine operating conditions.

A ring pack friction model has been developed based on the mixed lubrication concept to investigate the effects of ring surface topology on ring/liner interfacial frictions. The simulated friction results were verified by using the moving liner test rig and good correlations were established. The developed model was then extended to simulate the ring pack frictions under engine firing conditions. Surface roughness pattern oriented in the transverse, isotropic, and longitudinal directions were analyzed. The results indicate that the influence of surface pattern on ring pack friction is very substantial. A reduction of 9 percent of the ring pack friction is observed simply due to the surface pattern change. Friction reduction is a result from an increase in film thickness. This also helps to decrease the friction spikes near the dead centers and reduce ring wear. An increase in surface roughness magnitude significantly increases the ring pack friction.

The contribution of lubricating oil to diesel engine particulate emissions is of concern not only because of stringent particulate emissions standards but also because of engine-to-engine variability. Unburned oil contributes directly to the particulate soluble organic fraction. A real-time oil consumption measurement technique previously developed was further refined to also measure real-time unburned oil consumption. The technique uses high sulfur oil, low sulfur fuel, and fast response, sensitive SO2 detection instrumentation. Total and unburned oil consumption maps over the engine operating range are presented. Results show that both total and unburned oil consumption generally increase as speed and load are increased. Unburned oil consumption shows some peaks at intermediate speed, high-load conditions. Oil consumption from individual cylinders was measured and shown to be approximately equal.