Do not put mineral oil on snakes ever. It literally makes their scales fall off and not in a good way. I'm very confused how outside temp has anything to do with your snake shedding, I'm in northern MN and don't bath/soak or wipe down any of my snakes ever and they all shed perfectly on their own as they are supposed to. Are you using a fish tank type setup with heat bulbs? I'd highly recommend going to a pvc enclosure with a radiant heat panel, it's much more suitable to keep a snake at correct temps and humidity without all the hassle.