One of the most important utilization features of vehicle engine is its durability. Durability depends mainly on the wearing processes of frictional connections of engine elements.The studies of engine parts wearing can be divided into two kinds: quantitative and comparative according as the purpose is to define quantitative durability or comparison of the influence of selected design, technological and utilization factors.The present report describes distribution of metallic impurities coming from mechanical wear of parts in the combustion engine. Distribution of impurities between lubricating system and exhaust system is of nonlinear character. High nonlinearity appears in not fixed conditions of the engine. In the longer time interval of engine operation, the distribution proportions between oil, oil filter and exhaust gases are going to stabilize. The knowledge about impurities distribution process in the engine enables improving the tests of engine parts mechanical wear and the tests of oil filtration process in the engine.