I have a Cinelli quill stem in a Litespeed that has been frozen for 5+ years. Now that I want to change the stem (just as they are disappearing fast!), I really wanted to get the old one out, but it would budge. I dripped Liquid Wrench down it every couple of hours for two days, banged down on the set screw with a rubber mallet after a couple of the treatments, and -- Voila! -- it loosened up.