Mechanism of formation of antiwear films from zinc dialkyldithiophosphates

Recently developed experimental techniques have allowed better characterization of lubricant-derived antiwear and antifriction surface films. These techniques and the information obtained in earlier studies are being applied to fully formulated engine oils with the objective of assisting implementation of advanced fuel efficient and emissions friendly oil technologies. Published results from those studies were combined with some new experimental results and with background information from related experiments and from experiments delineating the antioxidant chemistry of ZDTP to yield a more global view of antiwear film formation. This more global view has allowed us to propose an improved mechanism for the formation of lubricant-derived antiwear films, which accounts for a substantial body of experimental data, together with some unique observations resulting from our own investigations.