ASTM D3525 Gasoline Diluent in Used Gasoline Engine Oils by Gas Chromatography
During normal operation of gasoline engines, some fuel may leak past engine seals and mix with engine oil. The rate of leakage may increase with engine wear. If excessive amounts of gasoline mix with the engine oil, the performance of the engine may decrease. This method determines the quantity of gasoline in service engine oils.
A known quantity of n-tetradecane is added to the sample, and the mixture is injected into a GC to achieve the separation as per the method. Detection is by flame ionization. The mass percent of gasoline is calculated by comparing the gasoline peak with the n-tetradecane (the internal standard) peak using a calibration curve. The best accuracy is obtained by submitting a new oil to be used as a baseline. Reported is mass percent of gasoline.