Waste Motor Oil in nonmultifuel engines
I used to pull for Fed-Ex overnight between Asheville & Charlotte, NC, would get behind a fleet of trucks that dumped their oil changes into the fuel tank. You could smell them for several miles before you saw them. Last I knew, the govt made them stop using waste oil. I have always been leery of putting the abrasives and contaminents that are in waste oil through the fuel system of a diesel engine.