CRC makes a product called Blaster. It's the best stuff I've found so far.

Any penetrating oil will work though, the trick is getting it forced into the area.

Airasol type spray cans will work about the best.

Use a LOT of it. DONT be stingy. Squirt the hell out of it, go back the next day and hit em again....If you have several days, Keep hitting it with the stuff and waiting. Time is you're best friend when it comes to soaking rusted bolts.

Wheel studs are pretty beefy though, being that it's a wheel stud and not likely to snap off, I'd soak em once, come back the next day with a genuine impact socket which is EXACTLY the correct size or is a very snug fit. Use a breaker bar and a long pole to slip over the top of the bar. Don't try to muscle it, you want to snap it. Get everything on there and ready and give her a good yank. It'll probably snap loose, not off.

Good luck

Wayne