Can You Use Dielectric Grease On Spark Plugs?

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What Is Dielectric Grease?

It is best to find out about dielectric lubricants before using them. In this way, you can use it correctly and avoid mishaps.

Dielectric grease is a water-resistant lubricant that is also known as a silicone lubricant. It is created by combining silicone oil and thickener. Silicone oil is mainly composed of polydimethylsiloxane, abbreviated as PDMS. As a result, it is usually a sticky, translucent white paste.

This grease is no longer conducive and does not harden. It will maintain this pasty, greasy consistency for the rest of its shelf life. Therefore, it will remain this way and will not become hard or complicated.

The chemical reaction of bare metal with oxygen in the air is known as oxidation or corrosion. If you live in a humid area, oxidation will become a problem in your car over time. It will reduce the voltage, causing lights to dim and other devices to malfunction.

In extreme cases, overheating can occur as the current tries to break through, causing the plastic to melt, short out, and spark. In the worst case, it can also cause a fire.

Silicone grease can help you solve all these problems. It acts as an insulator, preventing voltage leakage. As a result, it can help reduce voltage leakage in high-voltage situations, such as an engine ignition system.

It is also suitable for use in low-pressure conditions because it prevents oxidation of wiring, inhibits corrosion, and seals out contaminants such as salt and dirt.

It also benefits plastic and rubber connector components. The oil in the lubricant helps reduce outgassing in the oil in the plastic. As a result, the plastic does not become brittle. It also lubricates the rubber fittings, improving sealing. In addition, when the connector needs to be replaced, it is easier to disassemble.

What’s the Difference Between Dielectric Grease and Lubricating Grease? 

Since dielectric grease and grease are designed for different purposes, their manufacturing methods also differ. Unlike dielectric greases, which are usually composed of silicone and thickeners, greases are composed of lubricating oil, thickeners, and other additives.

Grease is a type of product used to lubricate machinery, automobiles, and other institutions. It contains lubricating oil (petroleum, vegetable oil, or synthetic oil), performance additives, and thickeners.

Grease is usually applied through Zerk fittings, which are small metal adapters with male threads that are used to filter grease into automotive or machine parts.

Will Dielectric Grease Worsen a Connection?

It is a common misconception that putting insulating grease on electrical connections will cause them to fail because the grease will seep between the metals. This is not correct.

Although dielectric grease insulates the metals and wires from outside intruders, the contact points are tight enough to keep the connection intact, and the grease is only replaced when necessary. That is, it is not necessary to spray massive amounts of insulating grease on the connector, as shown in some videos.

When To Use Dielectric Grease

Dielectric greases can act as lubricants, sealants, insulators, and protective agents in these applications when used in small quantities.

  • Battery terminals
  • Spark plug boots
  • Bulb sockets
  • Trailer connectors
  • General electrical connections
  • General plastic or rubber lubrication

Can You Use Dielectric Grease On Spark Plugs?

Yes, it can definitely be applied. But how you use it and where you use it can make a big difference.

Many of us mistakenly believe that electrical connections can be improved by applying silicone lubricant to wire terminals. That is a big mistake. The very name dielectric tells us that it is an insulator. Therefore, it should not be used directly on the contact surfaces of electrical connections (such as plugs and sockets).

It should be applied to the rubber boots where the spark plug is in contact with the ignition coil to prevent moisture and leakage.

Should You Use Dielectric Grease On Spark Plugs?

You should certainly do so. That’s why you should use silicone insulating lubricants on spark plugs, as well as the advantages of doing so:

  • It allows high-voltage current to flow smoothly through the spark plug.
  • Seals rubber boots to prevent sparks from arcing or grounding around them.
  • Helps prevent the boot from sticking to the ceramic part of the spark plug.
  • Keep the elements and moisture out of the spark plug boot to prevent corrosion.
  • If a non-stick lubricant is not used, the dust boot will be injected into the spark plug. Using a non-stick agent on the inside of the boot can make subsequent disassembly easier and less likely to break.

Where to put dielectric grease on spark plugs?

If you are not sure how to use insulating grease on the spark plug wires, carefully follow the steps below:

A small amount of silicone grease should be applied to the inside of the spark plug protective sleeve. Cotton swabs are the best applicator in this case. They will help you spread it evenly. Using circular motions, apply a thin layer. This will help ensure that the inside of the sleeve is well coated with anti-seize. Avoid applying the lubricant to the metal terminals.

You can also apply a thin coat of lubricant to the ceramic insulator portion of the spark plug for added protection. Also, be careful not to get lubricant on nearby electrical conductors.

You can also use your fingers if you do not have a cotton swab. However, put on gloves before proceeding.

Too Much Dielectric Grease On Spark Plugs

Although dielectric grease is ideal for electrical plugs because it does not conduct electricity and can form a tight seal, it is not necessary to apply too much grease.

In fact, if you apply dielectric grease until it becomes thick and sticky, your vehicle will most likely not start.

The purpose of the grease is to provide a seal and prevent high-voltage electrical leakage. Therefore, only a thin coat is needed on each spark plug.

Applying a thick layer of insulating grease will prevent it from fully entering the groove. Since the grease does not conduct electricity, the car is unlikely to start if there is no contact.

If you still cannot start the car after lubricating the spark plug, clean it with a cotton swab, reinstall everything and restart the engine.


Can I use dielectric grease on spark plugs threads?

The BRP manual recommends the use of anti-seize lubricants on spark plug threads, but the NGK catalog prohibits it because of the possibility of over-tightening. Consequently, as long as it is not over-tightened, you should have no problem using it. It helps prevent seizure and seals the threads to keep combustion gases in the cylinder.

So Does Dielectric Grease Improve a Connection? 

Insulating grease, on the other hand, does not conduct electricity and therefore does not improve connectivity. It does, however, help to maintain a good connection.

Can dielectric grease cause misfire?

Many people experience fires in their vehicles after using dielectric lubricants to replace spark plugs. This could be due to the use of too many anti-seizure medications. You can insulate the connection and prevent sparks from spreading. Therefore, use cotton swabs with caution. Safety is preferable to regret.

Is Vaseline a Dielectric Grease?

Dielectric grease differs from petroleum jelly in that it has a silicone base, while petroleum jelly is made of wax and minerals. Never use petroleum jelly in the car.

Can you use dielectric grease on spark plug boots?

It is, indeed. It is used to prevent the boots from bowing into the engine block. Also, because the protective cover and porcelain insulator adhere easily, disassembly is simplified. It also protects against corrosion.

Final Thoughts

Is dielectric grease necessary for spark plugs? Yes, it is. As mentioned above, use it correctly. This will keep your vehicle in good driving condition for a long time. Also, if you live in a humid environment, apply it to the outside of the metal equipment. This will help it function properly and prevent corrosion. Simply avoid the contact surface, and that’s it.


Hi, I'm the initiator and writer of this blog. Cars were and will be my first love, and my favorite hobby, that's why I decided to start this blog and write about my discoveries and techniques to improve my cars or repair them.