Over the years, many bench tests have been used to guide synthetic organic chemists in their quest for new molecules to prevent valve train wear. Which bench tests to choose has always been an important issue, especially when the goal is to prevent valve train wear in an internal combustion engine, a very complicated system. Essential antiwear additives in modern engine oils are zinc dithiophosphates (ZnDTPs) and, although these materials have been used extensively, the fundamental mechanisms of their chemistries are not that well understood.