Just bought a new 22 Silverado. I don't want it going the way my last one did (rusted wheel arches and frame rust). I have a date with New Hampshire Oil Undercoating. I have no qualms with doing that annually. My worry though is that their oil will soften and degrade the wax undercoating on the frame which (miracle) actually looks pretty good right now. Should I tell them to stick to the body only for the time being?