CHARACTERIZATION AND SPECIATION OF FUEL OIL DILUTION IN GASOLINE DIRECT INJECTION (DI) ENGINES

Fuel dilution in oil is a known issue for gasoline direct injection (DI) engines especially in colder climates and for customers with short, lightly-loaded driving cycles. In this work, oil samples were generated using a cold oil fuel accumulation test. Gas chromatography (GC) was used to speciate the hydrocarbons accumulated in the oil and characterize their quantity, type, molecular weight distribution, and volatility. Further testing and analysis was done to characterize the fuel hydrocarbons that evaporate from oil during engine warm-up conditions. The results demonstrate how the wide range of gasoline hydrocarbon volatility leads to different behavior in the accumulation and subsequent evaporation phases. Lastly, a model was created to extend this analysis and estimate the evaporation of hydrocarbons from the oil.