. "Re-refining motor oil Re-refining motor oil recycles the used oil through a conventional refining process, where it is cleansed of contaminants such as dirt, water, fuel, used additives and other chemicals and impurities, explains Matthew Gudorf, director, oil collections and products, Safety-Kleen Systems, North-America???s largest collector, recycler and re-refiner of used oil. ???The resulting" . . . . .