Just be cautioned by the Grant Cunningham article linked-to by Db45-70, that there are benzene compounds in motor oil additives, so you don't want it on bare skin, and especially don't want those carcinogens on children's skin, as they're the ones most likely to live long enough to suffer the consequences. This is something I did not know before. Also, note his comment about motor oils having poor corrosion resistance. That's probably because they have to flow and clean themselves off surfaces, so they can't stick too ferociously.