The wax trick is indeed effective. Before i hit any ruusted, and I mean rusted, bolt I hit it with Kroil or PB Blaster the night before. Then I heat it real well and pour or spit cold water on it while it is glowing hot. Then heat it again and use wax. Only thing that this did not work on wan an exhause bolt. At that point, it was getting a new one anyway and got out the angle grinder.