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Originally Posted by MNBoxster
Hi,
A couple issues. Plugs s/b changed out every 2 yrs. regardless of the Manufacturers claims. This is for 2 reasons: First, you actually get the chance to inspect them and insure that the electrode hasn't broken or such. Second, you'll never have the plug seize. Plugs are cheap (possibly the cheapest thing you can do to a Porsche), it's a false economy to let them run forever.
Using an Anti-seize can actually impede the grounding of the plug as it insulates the metal-to-metal contact. Most Anti-seize compounds will actually glue the plug in place as the 'grease' cooks off from repeated heat cycles. That is, unless you use a Hi-temp Anti-seize which actually uses a metal (usually Copper) to withstand the heat. But, now you have the interaction of multiple metals going on.
Also, 50% of the torque spec is to overcome the friction between the threads. All torque specs (unless otherwise stated) assume a dry thread. If using an Anti-seize, you need to reduce the Torque spec by 50%, not 30-40%.
If you properly torque the Plugs - Dry, change every 2 years, you'll never risk stripping the threads or having them seize. BTW, the Torque Spec for Dry Threads is 30+3 Nm or 22+2 Ft. Lbs. and should be set in two stages.
Hope this helps...
Happy Motoring!... Jim'99
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Well, this isn't the first time and it won't be the last, but I disagree.
Yes, you must use a high-temp anti-seize. And no, it will not "glue" the plug into the chamber. The correct anti-seize for a steel plug into an aluminum head is a copper-based high temperature anti-seize. Agreed with your comment about checking the plugs every couple of years, but I'm not sure what that comment was in reference to.
Yes, I have seen steel plugs seize into aluminum heads, and no, they weren't overtorqued or left for an unreasonably long time. The electrolysis between the two metals is what you're trying to eliminate by introducing the third metal (copper). Having to helicoil an expensive head is not something I'm willing to do AGAIN because someone forgot to use the anti-seize.
As I said though - to each his own.