Originally Posted by jake12tech

Don't bother with anything else at this point but a gator grip for rounded bolts (at sears they sell them) and attach it to an impact gun and get it off with the impact. If you do anything else it's just going to snap off in the head. I've done 3 sets of glow plugs on an om606 with an impact and walked a member through the process of using it with an impact and it works every time. There's absolutely no other way to do it other than impact that guarantees removal. Heat the engine up and bring it home with the impact.