Oil-based stains on clothes can be impossible to remove since grease can penetrate the fibers of clothes and become permanent. One way to effective degrease clothes is to use a heavy-duty remover normally used to degum items like sticky labels. Brands like Goof Off and Goo Gone are made with microemulsion formulas that quickly break down greasy messes without leaving any residue or markings behind. Simply saturate the clothing with the remover, allow to soak for at least an hour and wash as normal. It'll be as good as new.