Our original SCF-Tight-Binding quantum chemical molecular dynamics method was applied to the tribochemical reaction dynamics of the additives in the automotive engine oil. We successfully elucidated the chemical reaction dynamics of the Zn-DTP and Mo-DTC additives under the friction condition. Both the formation dynamics and function of the Zn-DTP and Mo-DTC tribofilm were investigated and the effects of both the friction and the nascent Fe surface on the chemical reaction dynamics were well clarified on electronic- and atomic-scale.