PB Blaster works, and so does Kroil, my favorite. Steam locomotive mechanics swear by it, especially after after spending a day in a hot front end and inhaling the fumes.
Torch will depend on how big the bolts are. I use straight propane on small bolts, say 1/4" or so. Anything over 3/8 really needs either mapp gas or acetylene.
Another method is to heat mildly, the apply pariffin, which does a good job penetrating. It also helps to use an impact gun.
