The possibility of predicting motor oil behavior at high and low (moderate) temperatures is shown, and based on this a model that allows prediction of deposit forming tendency of oil at high (HTD) and low (LTD) temperatures is built within the framework of formulation of a physicomechanical (or motochemical) approach. The specific nature of HTD and LTD formation is associated with the peculiarities of disperse phase behavior, which is realized in various degrees of filling of the phase surface by oil additives and is expressed in the difference of temperature stability of surface (protective) layers.