A question for experienced mechanics. My neighbor has a 1993 Grand Prix 3.1 ,aluminum heads 178,000 miles. It wasn't running too bad but he wanted the spark plugs changed. ACs, no plating on threads. When I got them out , they appeared to have been in at least 50,000 miles.Most of them were a little balky coming out, but a little back & forth and they were OK. However, the center rear one wasn't as cooperative. I got it to turn out some but then it would bind up. I shot some spray lube on it & kept working it back & forth. I got it so it would turn out 2 turns easily,then the next 1/4 turn it would start to bind up. At that point it felt like it didn't want to go any further. So rather than risk a $600 plug change, I just screwed it back in & called it good. So from your experiences,should I have forced the issue or would I have been dealing with aluminum shavings?

IMO you did the right thing. If it isn't yours, and you don't have business insurance (or can take the hit if something breaks), don't phuk with it. http://www.nastyz28.com/ubb/smile.gif

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350CID, Vortec 062 heads, Magnum 280, Performer Intake, Holley 650 DP, 3.42 rear w/ Auburn posi, 2600 Stall/TC
"Things are more like they are now than they ever were before."
Former U.S. President Dwight D. Eisenhower

I'd have asked the owner what they wanted.

I had a 94 Grand Am...changing plugs was a PITA....on my back, arm against the firewall, and reaching past where I can't see.

AT an angle http://www.nastyz28.com/ubb/wink.gif

But I got them in...Iw as always more worried about stripping the thread holes in the aluminum tightening them up.

Here is where anti-sieze compound is worth its weight in gold. Dissimilar metals and time equals trouble. Good choice to stop when you realized thread trouble. Sometimes you can save the threads but.....

I told the owner about it. The car wasn't running that bad,so he was fine with it.

You did the right thing. Aluminum is risky stuff. You can ruin the head if you force things. Leave the old plug in and replace the car. Aluminum isn't designed to last long like Cast Iron was.