Well not so much on freeing rust bolts but putting a compound on them so they always come free.
My father used to work in a foundry. The problem they had is if metal is heated and cooled continously the threads become corroded just the same as exhaust threads. They found that applying a mixture of graphite and oil always made the threads easy to remove. Its easy to apply because the oil makes it a paste, the oil does burn off but it leaves the graphite behind.
He had an old VW camper 1968 and he was always fitted exhaust systems due to corrosion. He decided to buy a stainless system so it would last longer, he coated the threads with the compound. Many years later it needed changing again due to the parts that weren't stainless corroding. The nuts holding the exhaust to the cylinder head had corroded with no signs of flats on them. A light grip with moile grips and they came of and the compound could still be seen on the threads. This is a good tip if you keep cars for many many years. I've applied it to my car though the turbo nuts and bolts aren't easy to access.
