Wednesday, October 27, 2010

Spark plug anti-seize

John:  From your past publications:  "Champion recommends using 2602 spark plug anti-seize. Use sparingly. Some also use C5-a copper anti-seize although we prefer the Champion product which is a water based graphite."
Champion Spark Plug Anti-Seize and AutoLite Anti-Seize contain graphite.  I suspect that Lycoming suggests not to use a graphite-bearing compound is because graphite can weaken aluminum.
Lycoming quotes the following in their "Lycoming Flyer" ( that "It is helpful to use anti-seize or plain engine oil for spark plug threads starting two full threads from the electrode, but DO NOT USE a graphite-based compound".
What is the proper anti-seize to use on spark plugs?

In aircraft the proper product to use is contained in the maintenance manual so there is no debate. In the case of Champion spark plugs it is 2602. This is also what every large maintenance shop I have ever been in uses so I don't understand why this would be questioned.

C5a is not only not a product listed in any of the manuals that I am familiar with but it is a bad idea for two reasons:
1. Spark plug antiseize does not contain any metallic particles that can enter the combustion chamber and cause preignition. (way back when they used to use a mica antiseize which is a mineral that prevents seizing and is also non-metallic so is preignition safe). Small copper particles are not something that one wants in an air cooled combustion chamber.
2. Spark plug torque specifications are based on using the proper lubricant (2612 for Champion) and any change in lubricant will change the friction and the torque/tension relationship. Proper torque for C5a is unknown.

The Lycoming flyer recommendation was most likely written by Joe Diblin ("engine joe") some 30 years ago so is somewhat dated. Although I agree with Joe. Graphite and water is an awful spark plug antiseize. I debated about bringing back the BG mica antiseize and selling it as it is a much better spark plug antiseize but the torque issue prevents me from doing so.)


  1. Anonymous7:14 PM

    Good Information!

  2. Anonymous9:28 AM

    How do you clean the plug threads to get the graphite to stick? From what I've seen so far it has to be medical grade clean to get it to stick.

  3. Scott Wasmer11:00 AM

    You really have not answered the question. The Champion manual says to use their anti-seize, which has graphite. The Lycoming manual says to not use graphite anti-sieze.

    Its the same old question we have on the hangar floor all the time - two conflicting manuals, which one do we follow? I can provide endless examples of this - and nobody will give us an order of precedence... thats why most of us say the hell with it, and just do what we know, or think we know is best. We are screwed either way.

  4. Excellent comment and I hope I'm not to hard on you but after 40+ years in this aircraft repair business...

    The attitude of "the hell with it." is not acceptable nor tolerated in the aircraft industry.

    Here's the step-by-step process when you are presented with conflicting information:

    1. The FAA Approved Maintenance/Service Manual for the Type Certificate Part you are working on takes precedence. This should solve most issues.
    2. If this does not resolve the issue then contact the manufacturer's service department for clarification.
    3. If this does not resolve the issue then see if AC43.13 covers the practice or industry custom. Not all maintenance practices are covered in manuals. Some go back to mechanic school or training and have become a industry custom. Be careful though on this one.
    4. If this does not resolve the issue then decline the job due to lack of approved data.

    Some of the best decisions I ever made were the times when I decided that I could not do the job.