Dielectric Grease on Spark Plugs

Dielectric grease is a simple compound of oil and silica filler that’s very hydrophobic and is excellent at sealing out moisture and preventing corrosion. It is an electrical insulator or dielectric, and while a popular material for batteries, power outlets, light bulbs and spark plugs, its use is often misunderstood. The trick with using a dielectric grease is knowing where to apply it to seal the electrical contacts from moisture ingress and prevent arcing while not impeding current flow.

Where to put dielectric grease on spark plugs

As mentioned above, because it’s an electrical insulator, caution must be taken on where to put dielectric grease on. Spark plug terminals are an ideal area as the grease applied here will prevent the spark from the ignition coil from arcing around the spark plug boot to ground. When doing this, you must take caution not to get any grease on the metal terminal, as this will hinder the electrical connection. You can also apply dielectric grease to the inside of the spark plug boot to add more electrical insulation. Figure 1 below helps to illustrate this concept.

Figure 1: Illustration of how to properly apply dielectric grease to spark plugs. At left, application of grease inside the spark plug boot, being careful to avoid terminal receptor. At the right is the application of grease onto the ceramic of a spark plug, being careful not to apply any grease onto the terminal.
Figure 1: Illustration of how to properly apply dielectric grease to spark plugs. At left, application of grease inside the spark plug boot, being careful to avoid terminal receptor. At the right is the application of grease onto the ceramic of a spark plug, being careful not to apply any grease onto the terminal.

Is Dielectric Grease Necessary for Spark Plugs?

Strictly speaking, dielectric grease is not necessary for spark plugs to function; however, as noted above, it is a cheap, easy-to-use material that helps ensure the current moves through the spark plug into the ignition system. MG Chemicals’ 8462 dielectric grease is available in multiple packaging options for your convenience and volume requirements. Please get in contact with Technical Support to discuss your dielectric grease needs. 

Our ninth video in our In Focus series looks at our 8462 dielectric grease. This grease is perfect for keeping water and other corrosive elements away from electronic parts and preventing electrical arcing. In the video, we demonstrate common applications with tips on what not to do.

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