Accumulation of polycyclic aromatic hydrocarbons in crankcase oil.

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in automotive crankcase oils. PAHs were not detected in the new oil; however, concentrations increased rapidly with usage in the gasoline engine of an automobile. The PAH distributions found were dominated by alkylated two- and three-ring compounds. The concentrations of these compounds increased until about 4000 miles and then levelled out. Four-ring compounds continually increased with miles driven, and the five-ring benzopyrenes were only detected in the oil used for the longest distance (about 5800 miles).