What The Heck Is Dielectric Grease?

And is it necessary?

A tube of Permatex dielectric grease on concrete.
Tony Markovich

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Dielectric grease is not an automotive necessity like oil or coolant, but it’s a popular product used in garages across the country. Most commonly applied on spark plug boots, lightbulbs, and battery terminals, dielectric grease is, in theory, a protectant like car wax. It’s not required, but it could help extend and maintain the life and quality of your vehicle and its parts.

Dielectric grease is just one of the numerous types of lubricants found in and around your automobile, and each one has a specific purpose. If you choose to pick up some dielectric grease, you can’t use it interchangeably with wheel bearing grease, or vice versa. 

The Drive’s greasy editors are here to explain what dielectric grease is, isn’t, and how it’s supposed to work. Let’s start with the basics.

What Is Dielectric Grease?

Dielectric, sometimes referred to as tune-up grease, is a viscous non-conductive waterproof substance used to protect electrical connections from corrosion and dirt.

What Is Dielectric Grease Made of?

Dielectric grease is most commonly made of a silicone base and a thickener. It typically has a slightly translucent grayish or milky clear color. Permatex dielectric grease lists polydimethylsiloxane and silicone dioxide.

A tube of dielectric grease.
Tony Markovich

With tubes, the cap punctures a hole to release the sealed grease.

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

Dielectric grease and lubricating grease are designed for different purposes, and as such, they are made differently. While dielectric grease is typically made of silicone and a thickener, the lubricating grease is made of a lubricating oil, a thickener, and other additives.

Lubricating grease is a specific type of product designed for the lubrication of industrial, automotive, and other mechanisms. It is formulated from lubricating oil (petroleum, vegetable, or synthetic), performance additives, and a thickener. 

Application of lubricating grease often involves Zerk fittings, which are small metal male adapters used to funnel grease to a car or machine’s parts.

Will Dielectric Grease Worsen a Connection?

There is a myth floating around that putting dielectric grease into electrical connections can cause them to fail because the grease gets between the metal. That’s not true. 

Although the dielectric grease does insulate the metal and wiring from external invaders, the contacts are tight enough to still maintain a connection, the grease is just displaced. That said, you do not need to squirt huge globs of dielectric grease into your connectors as you see in some videos out there.

When To Use Dielectric Grease

Dielectric grease acts as a lubricant, a sealant, an insulator, and a protectant when lightly used on these applications.

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

Permatex dielectric grease looks like a milky white gel.

Pros of Dielectric Grease

  • Helps prevent voltage leakage
  • Helps insulate the electrical connection in frigid conditions
  • Protects against water damage
  • Protects against corrosion
  • Protects against dirt and grime
  • Protects against heat damage
  • Protects against material bonding
  • Protects against electrical overheating

How To Apply Dielectric Grease To a Spark Plug Boot

If you choose to use dielectric grease (Ed. note, I don’t), you don’t need a lot to achieve its purpose.

  1. With the car in park and cooled down, pop the hood.
  2. Remove a spark plug boot.
  3. Clean the spark plug and the plug boot.
  4. Squirt the dielectric grease onto a piece of cardboard.
  5. Use a cotton swab to apply a small amount of dielectric grease around the inner wall of the spark plug boot.
  6. Put the plug boot back in place, and you’re good to go.

Sometimes You Need a Certified Mechanic

As much as The Drive loves to put the "you" in do-it-yourself, we know that not everyone has the proper tools, a safe workspace, the spare time, or the confidence to tackle major automotive repairs. Sometimes, you just need quality repair work performed by professionals you can trust like our partners, the certified mechanics at Goodyear Tire & Service.

Tune-up dielectric grease on the floor.
Tony Markovich

Dielectric grease is not a conductor.

FAQs About Dielectric Grease

You’ve got questions, The Drive has answers!

Q: So Does Dielectric Grease Improve a Connection? 

A: No, dielectric grease is not conductive, so it does not improve connectivity. It helps maintain a good connection, though.

Q: Yeah, But Is Vaseline a Dielectric Grease?

A: Dielectric grease is different from Vaseline, as it uses a silicone base while Vaseline is petroleum jelly, which is made of waxes and minerals. Don’t use Vaseline in your car.

Q: Then Is Dielectric Grease Necessary?

A: No, dielectric grease is not needed for any connections to work.

Q: Can Dielectric Grease Cause a Short?

A: No, it cannot. If anything, it will help prevent shorts.

Q: How Can You Remove Dielectric Grease?

A: CRC suggests using “petroleum distillates and chlorinated solvents.”

Let’s Talk, Comment Below To Talk With The Drive’s Editors!

We’re here to be expert guides in everything How-To related. Use us, compliment us, yell at us. Comment below and let’s talk! You can also shout at us on Twitter or Instagram, here are our profiles.

Jonathon Klein: Twitter (@jonathon.klein), Instagram (@jonathon_klein)

Tony Markovich: Twitter (@T_Marko), Instagram (@t_marko)

Chris Teague: Twitter (@TeagueDrives), Instagram (@TeagueDrives)

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