The ASTM Test Sequences have gradually gained recognition as useful tools for defining motor oil quality (1). For example, Sequences I, II, and III are being used to evaluate new motor oil formulations in 19 laboratories. They are also used in factory-fill and U.S. Army Ordnance motor oil specifications.

Although repeatability and reproducibility have been serious problems in some laboratories, others have established that satisfactory results can be obtained. Several variables that recent experience has shown to be important test parameters are discussed. Test modifications resulting from a reevaluation of these variables are included.