What is dielectric grease and why should I use it?

Saturday, April 8, 2017

What is dielectric grease and why should I use it?


What is dielectric grease? Why should I use dielectric grease? How do I use it? Dielectric grease is something used on automotive electrical connections. It is relatively unknown and has some misinformation floating around regarding it. In this House of Hacks video, Harley talks about the what, why and how of using it.

This is part of a collaboration with Mike at Tomahawk DIY. In his video, he shows how to change the brake light bulb on a 2005 Jeep Grand Cherokee.

With Tomahawk DIY, Mike is building a business dedicated to helping people Build Better Lives. A substantial portion of revenue is donated to organizations that focus on helping people build better lives in some of earth's most dire circumstances. Visit his About page to learn more about the mission of Tomahawk DIY and use this Amazon Affiliate link to help support that work: Buy Dielectric Grease.

For a written transcript, go to What is dielectric grease and why should I use it?

Music under Creative Commons License By Attribution 3.0.
Intro/Exit: "Hot Swing" by Kevin MacLeod at http://incompetech.com
Incidental: “Beach Bum" by Kevin MacLeod at http://incompetech.com

Special effects: livingroom_light_switch by AlienXXX at http://freesound.com



Hey, I wonder if Harley knows his brake light is out. That could cause a real problem.

[Door slam]

Hey Harley.


Did you know your brake light's out?

No, I didn't know that. There's a car store right around the corner. Why don't we go get some parts.

Yeah, it's a really easy fix. I'll show you how.

Awesome. Sounds great!

[Buying parts]

Today at the House of Hacks, we're going to talk about replacing light bulbs and using dielectric grease.


Hi Makers, Builders and Do-it-yourselfers. Harley here.

This is Mike from Tomahawk DIY and we're going to be talking about two things. One on his channel about how to replace a brake light and on my channel this videos going to be about what dielectric grease is and why you should use be using it.

In Mike's video, we put some dielectric grease in the fitting before putting in the new bulb.

In this video, I want to talk about what dielectric grease is and why we used it.

While shooting the bulb changing video, we ran into a problem that is a great example of why dielectric grease really should be used.

We'd taken the old bulb out, put the new one in and put the socket back in the tail light assembly.

When we tested it, it didn't work. After some checking, I found corrosion on the socket connectors.

Dielectric grease helps inhibit this type of corrosion.

If these had grease put on them at the factory, they wouldn't have corroded this way.

So what is dielectric grease?

It's a silicon based grease that is non-curing and non-conductive.

Coming out of the tube, it has a, well, greasy type consistency, and being non-hardening, it maintains this consistency.

It stays this way and doesn't get hard or setup.

Here I have the multi-meter here setup to measure resistance.

When I put a drop on the probes, we can see it is non-conductive until I press the probes together and they make metal-to-metal contact.

Bare metal will have a chemical reaction to the oxygen in the air, called oxidation or corrosion.

Oxidation is less conductive than the metal, causing the flow of electricity to be reduced.

If there's not much oxidation, the reduction isn't enough to cause a problem.

However, in the harsh, sometimes wet, environment of a car, oxidation can build up over time to be a problem.

At best, it will decrease voltage causing lights to dim and other devices not to work properly.

In extreme cases, it can cause increased heat as the current attempts to break through and cause plastic to melt, shorts and sparks and, in the worse case, a fire.

Dielectric grease does a couple things to help combat these problems.

First, it's an insulator and helps prevent arcing between air gapped metal.

In high-voltage situations, this can help reduce voltage leakage, like in the engine's ignition system.

But in the low voltage situation of lighting, this isn't it's primary benefit.

In normal use, any place there's air gapped terminals, the air is sufficient insulation.

It's primary benefit comes as a non-hardening sealant.

When it's liberally applied to an electrical connection, it coats the metal and surrounds the terminals.

But being squishy, it is pressed out of the way on the metal-to-metal contact points.

This creates a sealed electrical connection that prevents both air and water from getting to the metal.

Keeping the water out of the connector helps eliminate short circuits and keeping the air out limits corrosion from happening.

It also helps the plastic and rubber parts of the connectors.

The oils in the grease help minimize gassing off of the plastic's oils.

This in turn helps prevent the plastic from getting brittle.

It also lubricates rubber fittings to let them seal better but not fuse.

All these things combined make the connector easier to take apart next time the bulb needs to be replaced.

I've seen some more expensive cars with dielectric grease on fittings from the factory.

And I've heard of people who will go through their vehicle when they first get it and put grease on all the connectors.

Usually these are people who put their vehicles in unusually harsh circumstances, particularly off-road or marine environments.

Personally, I use it whenever I replace something, but I don't go out of my way to take things apart specifically to add grease to them.

But given this most recent situation, I may rethink that.

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