Topic: Anti-Seize Compounds on Spark Plug Threads

[KennyRedman]

I was just about to install my NGK plugs, wondering if I should use anti-sieze or not, and found this:

http://www.ngksparkplugs.com/pdf/tb-0630111antisieze.pdf

Tech Bulletin -
Anti-Seize Compounds on Spark Plug Threads

The use of anti-seize compounds on spark plug threads that have a metal shell
plating (i.e. Zinc or Nickel plating).

Issue
Applying anti-seize to the threads of spark plugs that have a metal plating allows the installer to
mistakenly over-tighten the spark plug in the cylinder head; This stretches and fatigues the threads of
the spark plugs, causing a much higher probability that the plug will break during installation or in some
cases upon removal.

Example of 10mm thread spark plug broken during installation due to the use of anti-seize leading
to over-tightening. (Note that plug gasket has been completely compressed, anti-seize can be seen
on threads, and the break is in the direction of tightening).

Solution
For spark plugs with special metal plating simply do not use anti-seize on initial
Installation; All NGK Spark Plugs are manufactured with a special trivalent Zinc-chromate shell plating
that is designed to prevent both corrosion and seizure to the cylinder head; Thus eliminating the need
for any thread compounds or lubricants.

Additional Information
NGK recommends only using spark plugs with metal plating on all aluminum head applications to
prevent damage to the head and plug. Metal shell plating acts as a “lubricant” which breaks away from
the main body of the spark plug during removal, preventing damage to the spark plug and or threads in
the cylinder head.


Summary
All spark plugs that have a blackened or dull appearance on the metal body offer no protection against
seizing or bonding to the cylinder head and so it is with these spark plugs that anti-seize would be
required. A spark plug that has a shiny silver appearance on the metal body usually indicates that the
plug is manufactured with metal shell plating and therefore will not require anti-seize.
Example of spark plugs that do not have metal shell plating
For more information, please visit us at ngksparkplugs.com

[BobbyR]

When you use an anti seize the torque value on any threads a re reduced by about 20% This is called a wet torque. You can use a small amount and just don't go animal.

I don;t use it on plugs since I change them every year.

[kghost]

"All spark plugs that have a blackened or dull appearance on the metal body offer no protection against
seizing or bonding to the cylinder head and so it is with these spark plugs that anti-seize would be
required."

I just anti seize them and don't over torque them.

[BobbyR]

If you are going to use older plugs or keep your plugs for a period of time anti seize is is fine. Most of them for hi temp are metallic and conductive. You want to keep it away from the electrode and the area of high voltage. 

Less is more in this case. You can put a thin stripe on one side starting a few threads above the bottom, the anti seize will distribute itself as you screw in the plug. You do not need much.

[bill440cars]

      I haven't used antiseize on anything, for quite some time now, but used to use it sparingly, on spark plugs, but that was years ago. I had no clue as to what could happen.