Is the plug stuck solid or have you been able to get any turns on it at all ? If it turns even part of a turn , have you tried penetrating oil with the plug unthreaded to that point ? I ask because if it is carbon build up or oil fouling that has gotten stuck to the lower threads , you can try to unthread as far as possible while continuing to let penetrating oil break up what is stuck on the lower threads . If this is done carefully and over time , you may have success at it. The trick is not to be forceful or expect it to happen quick. It can take minutes , hours or unfortunately longer with many repeated applications of penetrant. Took long once to get a threaded fitting from an intake manifold on a 4.3 liter my dad had once for a quick disconnect for a heater core pipe . After many applications and enough time to seep in and many hot/cold cycles , we got it out like a hot knife through butter. Praying it's not cross threaded . If it were , even an impact may break it . That's when your last resort is to drill with good carbon steel bits. That kind of work is usually done with the cylinder head off. Don't want shaving in your engine getting into piston rings. Let's hope this is not the case . Please be careful in your attempt to extract the plug . I know you don't want it to get ugly. I've never tried to heat and cool with a torch and cold wet rag and I don't even think it's advisable on cast iron as it can easily crack of done wrong so I won't suggest trying it unless someone knows how to do it safely. I'm not for that idea but it works with corroded fasteners. The only way I know is if the plug can move even a little to continue penetrating oil soaking until a little movement at a time can be gotten and repeat until the plug u threads. If successful , the threads must be chased with a spark plug thread chaser ( also used to chase oxygen sensor threads in exhaust manifolds). Please let us know if there is any movement or is it stuck solid. You can try a deep impact socket with a hand held impact tool that is struck with a hammer bit care must be taken . The trick is to try BOTH directions ( on and off ) to attempt to loosen. But penetrating oil os needed as you go to lube and keep the cast and steel plug cool or destruction is certain . Tearing up threads is one thing , cracking the head is worse yet. Take it slow and use best care. Wishing you best luck .
