Motiv's warranty advises not to store bowling balls in temperatures below 40 degrees or above 125 degrees. So Motiv is suggesting that you not use more than 125 degrees of heat when you de-oil your ball. My Nu Ball Rejuvenator has a gauge that goes up to 145 degrees, but to be safe, I keep the temperature at 125 degrees.
My Motiv balls do not shed a lot of oil in the de-oiling process. I cannot tell what plasticizer looks like, but I would be shocked if I removed any. I have not seen any weird ball motion at any time after de-oiling.