Stuck seatpost (I've tried everything)

with steel frames, ignore sheldon's or anyone's advice on cutting.

I've said it so many times before, use caustic soda if the frame is steel and the post is alloy. you need the post for leverage with any other method, cutting it off will not help if it is welded to the inside of the frame! ally reacts with steel and that's what happens.

If the post is just tight, then lubricant and leverage will work, after all, someone got it in there in the first place.

I have had a stem stuck in a fork in caustic soda for about a week... I didn't help much, it was still stuck.... cutting it took less than 2 hours.