1-Nitropyrene in used diesel engine oil

It has been shown that engine oil may contribute 16 to 80 percent of the mass of organic-solvent-extractable particulate matter in diesel engine exhaust. This raises the possibility that the 1-nitropyrene in the exhaust is coming from the crankcase oil, having formed or accumulated there. To evaluate this possibility, 1-nitropyrene exhaust emissions from a light-duty diesel vehicle were measured, along with the 1-nitropyrene content of its engine oil and of new oil. Results indicate that new oil did not contain 1-nitropyrene at the detection limit of 0.1 ppm. 1-nitropyrene did collect in oil to a concentration of 0.5 ppm at an oil usage and vehicle travel distance of 9000 km. Even though 1-nitropyrene was found in used diesel engine oil, this 1-nitropyrene does not appear to account for the 1-nitropyrene found in diesel exhaust emissions.