Too Much Dielectric Grease On Spark Plugs

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Dielectric grease is also known as tune-up grease. By definition, it is grease made up of silicone that is made to protect electrical connections from moisture and corrosion.

It is also used to provide electrical connections with protection against water and dirt. It is used in automotive tune-ups, vehicle wiring, and home electrical work. Dielectric grease also has outdoor and marine applications because it does not easily dissolve. 

The most common use of dielectric grease is for the lubrication and protection of spark plug wires and the rubber parts electrical connectors in motor vehicles. 

Because this grease is made of silicone, it is not advisable to use it on silicone plastics or rubbers since it will break them down with time. Furthermore, because silicone is not a conductor of electricity, it is also not advisable to use the grease between mating surfaces of electrical connections.

The fact that dielectric grease is a non-conductor of electricity is the reason why it is used on spark plugs during engine tune-ups. 

How Dielectric Grease Is Used On Spark Plugs

Dielectric grease is normally utilized when doing a thorough tune-up on either a diesel or gasoline engine.

To use dielectric grease during a car tune-up, you should apply just a smidgen of it inside each spark plug’s rubber boot and then smear it nicely.  

The objective of applying silicone grease nicely inside each plug’s tip is to stop high voltage power inside the boot from traveling outside and into the engine block.

The dielectric grease also provides a tight seal around plugs so that dirt and water cannot get in through the connection. Lastly, apply a coat of dielectric grease also makes it easy to remove spark plug boots. 

If you do not believe you can apply dielectric grease properly, you should work with a local mechanic to avoid issues or problems. 

Too Much Dielectric Grease On Spark Plugs

While dielectric grease is great for use on electric plugs because it does not conduct electricity and it provides a water-tight seal, too much of it is not very necessary.

In fact, if you apply dielectric grease to the extent where it becomes thick and goopy, your vehicle will most likely not start. 

The objective of the grease is to provide a seal and prevent high-voltage electricity from being leaking out. Therefore, just a thin film of it is enough on every spark plug.

Applying a thick film of dielectric grease will make it impossible for you to push the sockets all the way in. And because the grease does not conduct electricity, the lack of contact will most likely prevent your car from starting. 

If your car will not start after greasing your spark plugs, you should clean them out using cotton swabs and then set everything correctly before starting your car again. 

Does Dielectric Grease Go Bad?

A dielectric grease product is one of those products you will buy and stay with for a very long time.

It can stay for years. Some people tend to think that dielectric grease products automatically go bad two or three years after they have been opened.

However, this is not correct. If you have a dielectric product that is still thick and pasty, you should not shy away from using it.

It may smell funny but that is how they all smell. As long as the grease still looks and feels like grease, you can use it as long as you want.

With this said, you should also make sure you read the instructions on the product’s label. There may be ingredients in a specific product that make it ineffective after several years. 

The Best Dielectric Grease Products

  1. Permatex 22058 Dielectric Grease Tube 
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Permatex makes some of the most sought after grease products in the automotive industry. This because the company has a reputation for making extremely high-quality tune-up products. 

This right here is one of their top dielectric grease products. It is one that provides maximum protection against both moisture and corrosion. 

It is a great lubricator for spark plug boots and gaskets. And you can use it to tune up your motor vehicle, boat, or even motorbike. 

The best thing about this product is that despite being a high-quality product, it is quite affordable.

It also prevents high-voltage from leaking out. 

  1. CRC Opaque White Di-Electric Grease 

This is a versatile dielectric grease formula that includes a thinner. It is very difficult for you to apply too much of this grease because of the thinner included in it. So you can never have issues with too much grease when using this product. 

The best thing about this grease is that it is a lubricant, a sealant, an insulator, and a water-resistor.

What most people love about this grease is the fact that it provides protection both in wet conditions and in extreme heat. This makes it great for use on off-road vehicles and dirt bikes. 

You literally apply it on any electric connection to protect it from extreme weather and it will work. It will provide protection and insulation. 

Perhaps the most unique thing about this dielectric grease product is the fact that it can withstand extreme heat without losing its characteristics.

  1. Mission Automotive Waterproof Dielectric Grease

This grease is a superior quality protector against corrosion, dirt, water, and salt. It also provides wonderful sealing and can resist extreme temperatures of up to 570 degrees F.

If you buy this, you can use it on your car’s spark plugs, gaskets, and on your battery terminals. 

One of the most unique things about this silicone grease product is the fact that it comes with a special applicator that makes it easy to apply and makes it difficult to apply too much of it. 

I like the fact that this product is a good quality product that is affordable and has many uses.

  1. Permatex 81150 Dielectric Grease
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This is the second Permatex product on this list. Just like the previous one, this one too is a high-quality product.

It protects electrical connections from corrosion, dirt, and salt, it prevents voltage leaks and it is great for spark plug boots, battery terminals, and trailer hitches.  

One of the standout features of this product is the fact that it offers incredible resistance against water. 


Dielectric grease offers protection against corrosion to spark plug connections. It also offers prevents leakage of high voltage electricity from car engines.

While it is useful, too much of it can be a problem as the situation can prevent good contact between plug and engine. Therefore, apply only a thin coat of it if you decide to do so.