People say that burning used motor oil in a diesel will cause coking. What is coking and is it a problem?
Coking is the build up of carbon, normally on injectors and the head. Engines running on straight used oil that has not been properly cleaned can be destroyed by coking. It can actually lift a head right off the engine. When we make black diesel, we clean the oil and add additives that prevent coking. In hundreds of thousands of miles on black diesel, I have never seen evidence of coking when the fuel is made correctly.
