The shop guy in Portland showed me a trick for rusty seatposts and it saved me a frame
I was stuck on a 1987 Schwinn with a seatpost welded in by rust, and I mean welded, not just tight. A guy at a co-op on Alberta Street in Portland watched me for 10 minutes, then grabbed a can of ammonia and a strap wrench. He said soak it overnight, then twist slow, and that post came out in 40 seconds the next morning. I had been using penetrating oil and heat for two days before that. So what is your go to for a stuck post when nothing else works?