Thanks for the link. Great discussion.
I DO encounter this problem ... all the time. It is my standard protocol to soak, soak and wait, and wait and soak and wait on everything old and crusty before attempting to muscle something free. I have broken too many fastners stuck in too many holes and dealt with the ensuing hours of torch, drill, Dremmel, and Easy-out to not be patient and wait for the effects of solvents first (remember the Jij's tech night at Guy's and the bolt in the head?).
I buy cheapo penetrating oil from my favourite royalty, Princess Auto, but I will try this next since I have both some ATF and acetone kicking around.
Peace, ATF & acetone, Dennis