Awareness of engine oil condition is a valuable indicator for assessing the state of degradation of the lubricant. The article deals with monitoring of chemical elements, especially metals and additives, during lifetime of commercially distributed automobile engine oil Castrol Magnatec 10W–40. Engine oil was regarded as a Newtonian fluid. The passenger car Renault Scenic I with petrol engine (four pistons, volume 1,600 cm3) was used to the observed. Lifetime of automobile engine oil has been stated by car and lubricants producers in interval 15,000 km. The samples of automobile engine oil have been taken in suitable intervals – 1,500 km. Only first sample of used engine oil was taken with raid 20 km. The seasons of monitoring were spring and summer. The spectrometer Spectroil Q100 has been used to monitoring of chemical elements in automobile engine oil. Increase contents of metals and decrease contents of additives were observed. The results were modelled using mathematical models with given the values of coefficient correlation R. Linear function as a mathematical model with the lowest number of degrees of freedom was used. Created mathematical models can be used to predict of conditions of engine oil in the same or similar petrol engine aggregates.
MATHEMATICAL MODEL OF PETROL ENGINE WORKING ON ATKINSON CYCLE