Originally Posted by The Evil Twin
Do not EVER use anti seize on modern spark plugs. They do not need it and it affects the tightening torque.
I've read that in the latest $7.99 Chilton's Manuals too. Anti seize prevents and protects the soft Aluminum threads in the cylinder head from galling when the plugs are removed. This is extremely important in Aluminum cylinder heads. And the fact many of these Aluminum head engines are going 100K miles before a change is required, make the use of it an even greater necessity.
Also, dissimilar metals and a bit of moisture create electrolysis, and will corrode the interface junction. NOT a good thing. Anti-seize will not
prevent the threads from getting a good ground through the head, as some claim. In fact with the copper impregnated anti seize compounds, it actually will help increase it. I have NEVER heard of a mechanic at a dealership, or anywhere else say not to use it.
Personally, I have used anti seize compounds, (both Loc-Tite / Permatex C-5A and Never Seize brands), for over 45 years on every spark plug I've ever replaced in cars, trucks, boats, motorcycles, and ATV's, and have never had a single issue.... Ever. And this involves hundreds of spark plug installations over 4 decades. Many of which have had a small squeeze packet of anti seize accompanying the plugs inside the box. On the other hand, I've seen countless issues of galling along with the accompanied stripped threads that almost always result, on cylinder heads, (both Aluminum and cast iron), where it was NOT used. After 45 years without a problem, I've learned to stick with what works.