Antioxidant Decay in Engine Oils During Laboratory Tests and Long Drain Interval Service

A new method for the determination of antioxidant capacity in lubricants has been utilized for the analyses of new and used engine oil samples. The results derived from these analyses were used for monitoring the antioxidant decay during laboratory and long drain fleet testing and in various correlation studies. The application of the method provided new insights into the nature of the oxidative deterioration of engine oils as a function of type and initial concentration of antioxidant additives, of type of base oil and of test or engine severity.