Tried acetone and tranny fluid, many days of BP Blaster, torch, hammer, vice and dry ice and it didn't work on my stuck posts. Fastest way is to get it red hot and melting with the gas ax (aka blue wrench) and wrap it with a wet rag. The steam gets into the rust and boils it apart. Of course this ruined the frame, but I felt much better as my anger was taken out on the offending frame. Red hot molten puddles of frame steel also ruined my shoe soles. I twisted a down tube using a vice to hold a seat post once, ruined the frame. Since then I got gun shy and just drill them out with a big industrial drill and a long carbide tipped cement drill. Also used a large hammer drill, which works fast but the hole ends out larger then the bit. I then use a homemade drum sander and a lot of oil to hone it to final size. I work on this for about half and hour at a time. I get bored and come back to it. It takes many days to do this. I have done this to two frames so far and and I am working on another which is a lucky 7 that is welded into the frame. After I drill out the lucky seven I will never get another frame with a stuck seat post, they are the worst.