One could simply stop using anti-seize and torque to the factory recommended specs when using shiny metal shell plated plugs as per the manufacturers recommendations, and be done with it. Specifically, they state: "If a thread lubricant such as grease is coated on the thread, tightening to the recommended torque is tightening too much this has been linked to seal leakage. This increases the probability that the spark plug will either break during installation or upon removal.įor plugs without a special metal shell plating, NGK advises the use of anti-seize and provides photos of unplated plugs installed without anti-seize where the steel threads have bonded with the aluminum in the cylinder head requiring replacement or repair of the head.ĭenso also warns against the use of anti-seize in their Spark Plug Installation instructions: Applying anti-seize to these plugs will cause the installer to mistakenly over-torque the plug in the cylinder head stretching the metal between the last thread and the seal between the cylinder head and plug. For plugs with this special metal plating, anti-seize is not recommended during installation. Or, you can go directly here for NGK's take on the use of anti-seize compound, NGK Technical Bulletin #NGKSP-0907-1:Īccording to the Bulletin, NGK states that all their plugs are manufactured with a special metal shell (trivalent) plating to prevent damage to the cylinder head. I found this excellent Canadian website that lists the complete set of NGK Technical Bulletins. Intrigued, I went a-googling for any information I could find from NGK on this topic. Champion recommends that you do not use an anti-seize compound, since one has already been applied to the plugs at the factory. Our latest technology combines Tin Tac" and ULTRASEAL'M coatings over the plating to further reduce corrosion and seizure. Once the shell is formed and threaded, it is zinc-plated to extend its life and reduce the chances of seizure in aluminum cylinder heads. This prevents sharp edges which could cut new threads into aluminum cylinder heads. The extruded shell goes through a cold rolling process to form the threads. It can be accessed at:Ĭhampion spark plug shells (the threaded part) use an extruded steel to maintain exact tolerances. The following material is excerpted from the Champion Spark Plug Handbook. Over-tightening also results in extremely difficult removal. Over-tightening of a spark plug can cause stretching of the spark plug shell and could allow blowby to pass through the gasket seal between the shell and insulator. This increases the likelihood of pulling or stripping the threads in the cylinder head. The result of the lowered friction is that when the spark plug is torqued to the proper specification, the spark plug is turned too far into the cylinder head. Doing this will decrease the amount of friction between the threads. However, plug seizure is aggravated further when steel plugs are installed into aluminum cylinder heads for a long period of time.ĭo not use any type of anti-seize compound on spark plug threads. Autolite spark plugs are nickel plated to resist the effects of corrosion and seizing. This can lead to thread distortion and thread galling resulting in cylinder head damage. Anti seize compounds can also have a torque multiplying effect when installing plugs. If anti seize compounds come in contact with the core nose of the plugs, it can lead to a misfire condition. Anti-seize compounds are typically composed of metallic, electrically conductive ingredients. We do not recommend the use of any anti seize products for installing spark plugs. One member insisted that anti-seize should never be applied to spark plug threads and as evidence quoted the following information taken from Autolite and AC/Delco: While there, I came across a forum discussion on the choice and installation of spark plugs. Since he knows little about cars (other than he knows what he likes), he asked me to do some research for him on a BMW website. A friend of mine who has a lot more money than me is interested in buying an Ultimate Driving Machine.
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