The stuff I used was called Extrac-Alloy. And it did a good job on the 4 cylinder Wisconsin air cooled head bolts. It would heat the broken stud/bolt and get the rust to let go long enough to turn it out. Once you get a bead started on the end of the stud/bolt, you kept adding to it, until you get to the nut. Carry the weld bead to the nut and fill it in. I used Vise Grips to grab the nut and slightly try it back and forth at first, giving it longer and longer turns until it comes loose. Spin it out in one motion, don't stop. As it cools, it will grab again if you don't keep going. If you give it one big pull at first, I can guarantee you'll shear off the weld bead. You need to give it a few back and forth motions, to work harden the bead. It will toughen up and allow the stud to loosen and turn out. Used it on a few other items, and it worked well. Welding upside down is a real bear, hard to control the bead, vertical is so so. Horizontal is the easiest. I liked it, saved a pile of money on labour, did everything they said it would. Sniper