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[Crotalus]

sonof40 previously said:

Thanks for the tip. I hadn't heard of them either. Vice Grips also do the job.

Nope, I'm a vice-grip expert. When trying to remove the already-rounded plug, we spent an hour on it and used all manner of monster vice-grips, impact six-sided sockets, etc. and all it did was continue to round off the head. The Irwin socket worked the first time.

It was a new/used truck for my buddy, turns out some numbnuts (probably at a shop because the previous owner never changed her own oil...) did not put the washer (a galvanic isolator?) on the plug - galvanic action most likely led to corrosion causing the problem.