Abstract: | In recent years the role of laboratory methods in investigating the effectiveness of engine oil additives has dramatically increased, especially in predicting the performance of engine oils under field conditions. Some results of research under laboratory conditions on the ageing of engine oils with different performance levels are presented in this paper. The role of the action of antioxidant additives in engine oils for gasoline and diesel engines is described. The paper includes the results of experiments over time in laboratory testing of doped motor oils, use of IR spectroscopy, and reference oils. Single‐ and multi‐cylinder engine test results are also discussed. New, effective additive packages for different engine oils are considered. |