cx: sounds like some good bits of advice. To add to the rest: get yourself a known-to-fit replacement plug. Then get on your back, assuming that the car is not on a lift (do you at least have the back tires up on a ramp, or SAFELY elevated so that you have a little swingin' room?), and get a medium-sized BFH, and after heating the plug, which has been PBBlasted overnight, give the ole plug a couple of love-taps, then try TIGHTENING, just a little bit, like 5 degrees or so, and THEN try loosening it. That almost works for me. This IS one of those cases where The Bigger Hammer/Bigger Vise Grips/Bigger Pipe Wrench Theory comes into play.Let us know the sequence of methods/tools used, and what finally "did it." Good Luck amigo.--PD