What Is Dielectric Grease?

How to Use Dielectric Grease

Before taking steps to apply dielectric grease, you should remember the following important things:

• Wear gloves and protective eyewear, because it can be an irritant
• Apply in a well-ventilated area
• Avoid applying it to the mating surfaces of your electrics such as pins and sockets

Step 1: Put on your gloves, and eyewear and take a cotton bud as an applicator. You only have to add a very small amount of grease to the end of your cotton bud stick. The stick makes a great precision applicator and will afford you the best control, which is important when applying.

For the next stages, we will divide the processes up into specific applications:

Connectors and Multi-Pin Connectors

Step 2: Separate the pins from their connector.

Step 3: Apply the dielectric grease around (but not touching) the mating surface. Apply lightly because even a little too much threatens pushing it into the pins, which would be bad.

Step 4: After careful application, plug the pins back into the connector.

Battery Terminals

Step 2: Remove the battery and clean the battery terminals before application. Use a wire brush because it will better remove any residue or grime buildup.

Step 3: Use your cotton bud to apply the grease lightly and sparingly to the terminals. If you feel the cotton is too small here, you can use your finger, so long as you’ve disconnected the battery.

Step 4: Replace the battery.

Light Bulb Sockets

Step 2: Remove the light bulb from the gasket lens.

Step 3: Apply the grease sparingly using your cotton bug; press very gently and try to move in smooth, circular motions.

Step 4: Reconnect the light bulb.

This same process will work for headlights, brake lights and turn signals to help keep out moisture and corrosion.

What is Dielectric Grease Made Of?

The principal ingredient in dielectric grease is silicone, which is then combined with thickeners to create the texture. The color is usually gray with a translucent appearance. The most common silicone used is polydimethylsiloxane (PDMS) and the thickener used is typically amorphous fumed silica.

Dielectric Grease Applications

This simple-looking silicon grease has many applications within your vehicle. It can be used on the following engine parts: spark plugs, connectors, battery terminals, light bulbs, ignition systems and others.

What does it do for these components? For spark plug boots, it prevents them from getting stuck to the ceramic portion of the spark plug after a long time sitting there. The grease keeps the seal between them free of contaminants and provides resistance for the boot to the high temperatures generated by the spark plugs.

In your vehicle’s ignition system, the dielectric grease is very effective against voltage leaks and lubricates and seals rubber parts belonging to the electrical connectors. It’s also very effective protection for light bulb sockets and battery terminals against the effects of oxidation.

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

These two greases are not designed for the same purpose, and they aren’t made in the same way. The base ingredient of the latter is lubricating oil, which could be petroleum or vegetable-based, or synthetic. Dielectric grease is made using silicone oil. The lubricating effect of dielectric grease is typically greater than that of regular lubricating grease.

They have other differences in key properties as well. For instance, the lubricating grease is conductive whereas dielectric grease is not. In addition to that, the lubricating grease is less able to stand up to high temperatures than dielectric grease and typically features ingredients of much lower melting points. The high melting point of dielectric grease makes it perfect for those applications.

Dielectric grease is also insoluble in water, ethanol, mineral oil and methanol, unlike lubricating grease. Therefore, it is more suited to outdoor applications, and even marine applications.

On the flip side, dielectric grease is more costly than regular lubricating grease, but that is hardly surprising given its more durable qualities and better scope for use in sensitive applications such as on electrical parts and components.

Will Dielectric Grease Worsen a Connection?

In general, no it won’t. Only if applied to the mating surfaces will it cause problems in connectivity and current, otherwise it will work very well and protect electrical connections from the effects of corrosion, which is what would otherwise damage them the fastest.

Dielectric grease is an insulator, but as long as it’s not applied too thickly to electrical connectors, then it won’t worsen connections.

When To Use Dielectric Grease

You should make use of dielectric grease when you need a sealant, insulator or lubricant in any of the following areas:

• Spark plug boots
• Trailer connectors
• Light bulb sockets
• Battery terminals
• General electrical connections
• Plastic or rubber connectors in need of lubrication

You shouldn’t apply it too generously, nor should you apply with a large or thick applicator. A cotton bud tip is a perfect DIY applicator tool. You should also avoid applying dielectric grease if you have no prior experience or guidance on how to apply it correctly.

Pros of Dielectric Grease

The first pro of dielectric grease is that it can better preserve your spark plug boots. By applying the grease both in a thin layer to the inside of the boot, and to the ceramic part of the spark plug, you can ensure that when it comes time to remove the boots, the process is much easier, and will greatly reduce the risk of damage to the boot.

Second, it provides a superb seal on metal surfaces. The seal created by this silicone grease protects sensitive electrical connections and their metal surfaces from the destructive effects of corrosion. It can also withstand very high temperatures of up to 500 degrees Fahrenheit.

Third, while it protects plastic and rubber from wear and tear (see spark plug boots above), it also protects them from fire. The layered coating on the connecting layer prevents oxidation and stops wear between them and the mating surfaces. The heat insulation in particular is effective at keeping heat-sensitive components protected.

Fourth, it prevents insulating oxide layer buildup. When the connectors’ metal parts are left exposed to the air, the process of oxidation forms a buildup on the surface, which eventually begins to insulate the connection and thus create greater resistance.

Finally, it provides lubrication where regular grease can’t help. Regular grease is applied widely across many mechanical parts in cars, as well as in industry. For electrical systems that are more demanding in their protective needs, lubricating grease just won’t cut it. It doesn’t provide the protective strength that dielectric grease gives.

Cons of Dielectric Grease

First, accidental application of grease to spark plug terminals can cause overheating and greater electrical resistance. Many first-time users when applying the grease may accidentally get some on the metal terminal inside the spark plug boot, or on the spark plug itself. It can have terrible consequences and so requires great care when DIY applying.

Second, the risk of the first problem prompts the greater need for a certified mechanic. This can mean additional costs for you if you’re worried about doing damage to the electronic components of your vehicle.

Third, dielectric grease is an irritant. When using it, users should wear protective eyewear and gloves, because if it gets onto the skin it can cause serious irritation to both eyes and the skin, which is rather unpleasant. Beyond superficial irritation, dielectric grease often produces formaldehyde, which at higher temperatures can even cause damage to the respiratory system.

Finally, it can react badly with silicone rubber over a long time period. When applied to silicone rubber and left for a long time (typically years), it can cause the silicone rubber to melt. It’s best to avoid being left on silicone rubber for longer periods of time, therefore.

How to Apply Dielectric Grease To a Spark Plug Boot

Below we will introduce how to apply dielectric grease to your spark plugs. Please remember, however, that making mistakes in this application can cause problems with the spark plugs. Therefore, if you have any doubts in your confidence to get the job done correctly, then seek the help of a professional mechanic first.

Step 1: Identify the appropriate greasing area. Dielectric grease is an insulator and therefore if you apply to areas where currents are flowing, IE the mating surfaces such as pins and sockets of electric connections, it will cause disruption, even causing the current to become unable to reach its destination. The first step is to identify which parts are safe to grease. These parts have no electrical currents passing through. On the spark plug, that means applying it only to the inside of the spark plug boot and the ceramic portion of the spark plug.

Step 2: Take a cotton swab to use as an applicator, and apply a small amount of dielectric grease to the tip. Apply a thin coat to the inside of the boot using a circular motion, being careful not to touch the metal terminals. The coat should be very thin.

Step 3: For additional protection, add a small amount of grease to the ceramic portion of the spark plug. Use the same careful circular motion and be careful not to get any grease on the metal terminal.