The growing use of tribotest has been helping the researches to understand the actuation mechanisms of additives on the friction and wear control of engine parts. But, it is common to observe differences between the tribofilms formed in real situation from that obtained using tribotests. Furthermore, the automakers have difficulty to correlate the results obtained using tribotests with that performed using engines in dynamometers. For the piston ring/cylinder bore tribosystem is almost impossible to reproduce its real tribosystem using tribotests. Therefore simplifications are necessary and they affect the tribochemical behavior of the tribosystem. To understand how these simplifications and the test parameters affect the tribochemical behavior of the simplified tribosystem is critical to design a tribotest that correlate well with the real situation.