[Jbabic]

spray some liquid wrench or your favorite type of spray, and let it sit. plus the more you work it, the more heat you generate, cause it tougher to come out...take your time and you'll be saving big $$$ in the future. when you install the new plug, put some antisieze on the threads and go back and forth, till it becomes easy to go another 1/8 turn...keep going back and forth only go forward slowly when its easy to turn....this will redo the threads...I had the same problem....