There is no evidence (aside from anecdotal) to suggest that rubbing used motor oil on your dog will accomplish anything, other than making him stink and introducing lots of toxic junk into his (and your) system.stonerebel said:The best way to cure the mange is change the oil in your truck or car. Take the used motor oil and cover the spots real good every day, in two weeks time no mange and the hair is growing back. I have used this on dogs and hogs works very well.