I should have been more specific regarding the fact that when galvanic corrosion occurs between an aluminum head and a spark plug with a bare-steel (uncoated) body, it is the threads of the aluminum head that serve as the anode, which corrodes in that electrochemical system. On the other hand, when I say that there is no risk of corrosion when a coated spark plug is used, I mean that there is no corrosion of the aluminum cylinder head -- it is the zinc coating (the anode) on the spark-plug threads that corrodes away. Once that coating is gone, the aluminum head becomes the anode.

Does anti-seize affect the heat range of a spark plug, making it run hotter? Personally, I don't see how this is possible if the spark plug is properly tightened. When the plug is sufficiently tight, there is metal-to-metal contact between the threads of the plug and the head, establishing the needed thermal and electrical conduction paths. Moreover, there is also thermal and electrical contact between the seat (base) of the plug and the head. Just in case, though, thermal conductivity of Copper at 212 deg. F = 218 Btu/(hr.ft. ∘F), Aluminum = 126 Btu/(hr.ft. ∘F), Graphite = 70-140 Btu/(hr.ft. ∘F), Zinc = 63.9 Btu/(hr.ft. ∘F), and Nickel = 33.5 Btu/(hr.ft. ∘F). So, if you are concerned with heat transfer, but want to use anti-seize, you can choose your poison accordingly.

As far as electrical conductivity is concerned, according to one source, resistivity (ohms/m) of Copper = 1.68 x 10neg8, Zinc = 5.90x10neg8, and Graphite = 2.5x10neg6 to 5x10neg6.

Now, if you have a loose plug, that is going to cause all kinds of problems.

Another advantage of using anti-seize is that it prevents galling of the aluminum threads.


























dissimilar metals
anti seize
Never Seize
copper
zinc
aluminium
nickel
grease
Suzuki GZ250 GZ 250 Honda Nighthawk 750 CB750 Harley-Davidson HD Harley Yamaha, Kawasaki