DIESEL FUEL DILUENT IN USED DIESEL ENGINE OILS BY GAS CHROMATOGRAPHY: ASTM D3524
EXPLANATION
Some fuel dilution of the engine oil may take place during normal operations. However, excessive fuel dilution is of concern in terms of possible performance problems. This test method covers the determination of diesel fuel as a contaminant in used lubricating oil. This test method is limited to SAE 30 oil. This test method may be applicable to higher viscosity grade oils. However, for such oils the precision statement of this test method may not be applicable. When testing unknown or mixed brands of used engine oil, the precision of the method may be poorer than the precision obtained when calibrating with a new oil representative of the used oil being tested.
TEST SUMMARY
A mixture of n-decane and used lubricating oil is introduced into a gas chromatographic column that separates hydrocarbons in the order of their boiling points. The column temperature is raised at a reproducible rate and the resulting chromatogram is interpreted for diesel fuel dilution.
TEST PRECISION
This test method has a repeatability of 0.3 mass % and a reproducibility of 1.6 mass %. This precision is based on the use of electronic integrators to measure areas and may not be indicative when other means of measurement are used. Because of the empirical nature of this test, no estimate of bias for this test can be made.
