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Originally Posted by John V
I would never skip anti-seize on an aluminum head car. Steel threads into an aluminum head? I would not risk it. To each their own.
When using anti-seize, reduce the tightening torque by 30-40% and you won't have any concerns about thread stripping.
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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