I’ve done and witnessed many of these things myself.
With cheater bars, I’ve noticed that whatever they are hooked up to, they may be more sturdy than the nut, bolt, you are trying to loosen or even in some cases the socket and its wrench as well…
My buddy has air tools, and they usually do the trick, however there are those jobs where it even states you are supposed to use it, but given the quality of the parts and a few decades of really anything it just didn’t work out.
As far as miracle chemicals go, we’ve all heard of wd40 and p blaster but I didn’t know about the seafoam equivalent.
Hagerty Kyle could have the right of it a combination of brute force and alternating between extreme temperatures which is why I have a can of freeze off in my shed.
I tend to use heat rather sparingly, most of my rides tend to be either on the leaky gasoline side or the magnesium engine block side.