The specialists emphasize, that the selection of oil viscosity should be carried out strictly within the range prescribed by the manufacturer. Too watery oil will not be able to form a stable oil film, and this fact will definitely lead to increased wear of engine parts. In addition, such oil will quickly burn out. On the other hand, too viscous oil will not reach all the friction surfaces effectively, which will also cause excessive wear. Besides, it will be difficult to start the engine. Remember, motoroils viscosity is determined according to SAE.