another + for kroil. also marvil mystery oil is very good, it comes in a gallon can and you can buy it at a.z and advance. read the can too good for lots of other things.

 

My dad and I have had good luck with this stuff:



It freezes the rust so it gets brittle and breaks loose.

Rob

 

At the nuke plant where I work, the shops use methyl salicylate (oil of wintergreen). I've used it a few times, and a little does go a long way (you typically apply it to the nut/bolt with a small syringe). It is expensive, though. Does it work better than PB Blaster? Not sure... I've had good luck with PB Blaster as well, but wintergreen seems to work a bit faster.