if you are really worried about tearing up the bolt leave the nut on. unscrew the nut so that its even with the end up the bolt. then get a BMFH and whack the shit out of it. this might free it up. if this doesnt work then who cares about tearing the bolt up. beat the holy shit out of it so that you can get it out, then go buy a new one. its a pain but you may have to. i bought a cr500 dirtbike with a swingarm pivot bolt stuck. it was impossible to get out. i tried heat, hammer force, and even putting it in a press. in the end i had to turn the bike over and cut it with a hot saw. talk about a pain.