Put them on the soak cycle with your regular washing soap and a quarter cup of ammonia. Then put it through the cycle. If the oil smell is gone was it again as per usual and no ammonia. That is what has been working for me. Fabric softener (scented) only add to the problem. I have been using Seventh Generation softener dry sheets and will discontinue because they leave a residue in my dryer. One half sheet will go through 3 loads but not liking the residue. I have alternated with using a sponge soaked in white vinegar (squeezed out of course) and like the results from that. I don't use the Mr. Clean eraser sponge. the microfiber falls apart.