Regular ole furniture paste wax. Forget about that blue stuff that comes in the kits. Paste wax is ten times the release agent the blue stuff is.

It is sooooooooo much easier to clean off too. A propane torch to just melt the wax and wipe off with a clean rag while it is melted. No scraping and trying to peel that blue crap off and worrying about scraching your metal parts.