In this study, a test system is developed in order to determine the effect of interference on the lifetime of the sealing element. A set of experiments are carried out with thermoplastic polyurethane radial lip seals with three different inner diameters varied by lip surface tolerance (40, 39.80 and 39.60 mm), and EP gear oil is used as lubricant. In order to determine the lifecycle of the sealing element, mass of the leaking oil is measured. Meanwhile, in order to determine the frictional performance of the sealing element, four load cells are mounted on the cylindrical housing of the system and frictional force values are monitored by a data acquisition terminal and frictional torque values are calculated. As a result, the frictional moment values of the seals increased with the increase in interference. Moreover, the increase in interference leads to a longer service life.