EN
This paper presents an original method for checking influence of lubricating oil improvers on performance of crankshaft seals of combustion piston engine. Crankshaft seals were tested with the use of a modified friction node of T-02 fourball apparatus in laboratory conditions. The tests were conducted according to a worked-out algorithm. Their results confirmed usefulness of the method for determining „harmful” performance of sealing systems, which makes it possible to assess operational usability of lubricating oil improvers. On the basis of an analysis of the results a scientific hypothesis saying that lubricating oil quality affects correctness of performance of crankshaft seals of combustion piston engine, was formulated. The hypothesis was verified by means of induction inference and statistical method with taking into account Fisher statistics