removing rust bolts

I need to replace the exhaust pipes from the manifold to the rear and they are really rusty. The pipes fell apart when I started to remove them to rebuild the transmission. Is there a good or preferred way to do this without braking the bolts? I used a nut buster product yesterday and thought I would spray them again today and maybe try to remove them in the morning.
While at the farmers market this morning I overheard a man who is working on a 55 corvette who said if you sprayed brake fluid on the old rusty bolts and let it sit for a couple of days you could remove any rusty bolts easily. Has any one tried that or have any other ideas?
as always, THANKS FOR YOUR HELP.