Should You Grease Car Battery Terminals?

We may receive a commission on purchases made from links.

Grease is slippery stuff well-known for its lubricating qualities — usually. However, when we're talking about greasing your battery terminals, we mean dielectric grease, which is used to prevent rust, dirt, and corrosion. It's still pretty slippery, but that slickness comes from it being made with silicone, not a petroleum-based product like typical lubricating grease.

When you apply dielectric grease to your battery terminals, the silicone helps make a strong, waterproof barrier between the environment and the metal of the terminal, preventing corrosion. It actually acts like a sealant that keeps water and air from touching the terminal and initiating the chemical reaction that results in corrosion (while also protecting against other damaging materials).

Now, some people say it also seals the terminal from electricity, in the sense that dielectric grease isn't a conductor, so it can cause connection problems if it gets between the terminal post and the battery cable. Well, that can be true enough, but it's simple to avoid by making sure you aren't using it wrong. You only have to apply the grease to the terminals sparingly, and then make a good mechanical connection between the components. That way, the pressure of the cable connector squeezes out excess grease to allow good metal-to-metal contact.

When should I apply dielectric grease to my battery terminals?

Proper — and regular — battery maintenance is vital to the life of your car. After all, in most vehicles, that's what gets everything going, literally. Although it also supports your accessories with the engine off, your car's battery is primarily used to power the starter, a small electric motor that gets the engine turning to begin combustion. A dead battery means that, for all intents and purposes, your car is dead, too. (A best-case scenario is you have a portable charger with you, but if not, here's what you can do.)

The potential for being stranded by a bad battery is why you should be cleaning your car battery terminals on a routine basis. And once you're done safely and properly scraping off the crud and corrosion, you should rub a small amount of dielectric grease on your nice clean terminals before reconnecting them. Don't have any handy? First off, just know that it can be pretty inexpensive, like under $10 a tube for the highly rated Permatex brand. Silicon-based synthetic grease can be used instead, but don't be tempted to use Vaseline or another petroleum jelly. The petroleum in it can harm rubber and plastic, or even combust if it gets too hot. 

What else can I use dielectric grease for?

Dielectric grease's unique properties also do more than just help it keep the environment out. It also helps keep the electricity in. This prevents the electricity from following a path it shouldn't, lessening the likelihood, for example, of getting shocked. The wayward electricity also has the potential to bond materials together in the same way an arc welder does. When you combine the dielectric benefits with the sealing power of silicone, you get a material that keeps electricity in, and dirt and moisture, as well as heat and cold, out.

As a result, there are a lot of other good automotive uses for dielectric grease. You can apply it to the spark-plug boot when you change your spark plugs (and here's how often you should change them), add it to bulb sockets, and put it on trailer connectors and pretty much anywhere else you want to keep the electrical connection isolated in both directions.

Note that it's in these non-battery applications where the advantages of dielectric, silicone-based grease over petroleum-based stuff really makes a difference. There's not much rubber or plastic around the battery for petroleum jelly to affect, but those materials are used near many other types of connections — like the spark-plug boots mentioned above — where protecting against cracking and drying rubber/plastic is vital. You don't want petroleum jelly putting you on the slippery slope toward a car repair.

Comment(s)

Recommended