More support for ATF and acetone, although MEK, or lacquer thinner, or mineral spirits all seem to work in a pinch.
Recently took off a bunch of nuts and bolts on a tractor blade that had sat outside in the weather in Georgia, near the coast for a
few decades. Soaked in ATF/laquer thinner for 10 min and got all of them off without breaking a one. It surprised me, and I
have been a believer for quite some time in this stuff.
I mix up a tiny batch whenever I need it. Hard to keep acetone or MEK or lacquer thinner
inside anything but metal cans.
Bill