That, and lots of heat! Most of us don't have an oxy/acetelene torch, but a Mapp gas torch is the next best thing, (much hotter than propane) and nowhere near as expensive. Some also swear by heating it up, and then applying candle wax, the heat sucks the wax into the hole. Haven't tried that one yet. Also rock the nut or bolt back and forth while it is red hot, loosening and tightening, loosening and tightening until it comes out.