We demonstrate the applicability of pyrolysis using microwave heating to recycle used car engine oil. Waste oil was thermally cracked in an inert microwave-heated bed of particulate carbon from which oxygen was excluded, and the relationship between temperature, the chemical composition of the hydrocarbons, and the metal fraction produced was determined. A reaction temperature of 600 C provided the greatest yield of commercially valuable products: the recovered liquid oils were composed of light paraffins and aromatic hydrocarbons that could be used as industrial feedstock; the remaining incondensable gases comprised light hydrocarbons that could potentially be used as a fuel source to power the process. In addition, the recovered liquid oils showed a significant reduction in the metal contaminants accumulated throughout their use cycle: a 93-97% reduction in Cu, Ni, Pb, Zn, Fe; a 46% reduction in Cd; and a 32% reduction in Cr. Our results indicate that microwave pyrolysis shows exceptional promise as a means for recycling and treating problematic waste oil.