ME 4! I use the TCW 3 in my fuel. My brother has a cummins and he uses used oil in his truck. It is the worst sounding diesel engine I might have ever heard. He does filter it before using but there is no way in hell I'm putting it in mine. There are people using WVO in our engines (7.3). They say they are well suited for it. It needs heating or warming in the colder months.