"AutomotiveNerd is supported by its readers. Please assume all links are affiliate links. If you purchase something from one of our links we make a small commission from Amazon."

Does Brake Fluid Eat Silicone? (Answered)

does brake fluid eat silicone

Imagine you are walking up to your car and you see a small amount of shiny liquid on your tire or rim. When you lean down to inspect the fluid you notice that it is brake fluid. Is Brake fluid harmful to rubber? Can brake fluid harm your rims? Does brake fluid eat silicone? 

Modern brake fluid is glycol-ether based and is not harmful to rubber or silicone parts. However, brake fluid is harmful to paint and will cause damage to painted surfaces in a short amount of time. 

Below we will take a closer look at brake fluid and what it may be harmful to your vehicle. 

What is Brake Fluid? 

Brake fluid is a hydraulic fluid used in braking systems or cars, motorcycles, and light trucks to transfer the force to the brake pedal into stopping your vehicle.

It is clear in color and can become dark or brown when it is dirty.

Different Brake Fluids Types 

There are different types of brake fluid available today. 

The most commonly used brake fluid is DOT 3. It’s a glycol-ether-based fluid. It absorbs water and can promote corrosion of metal found on the brake lines and cylinders of the braking system.

DOT 4 brake fluid is commonly used on newer cars and trucks. It has a higher boiling point and doesn’t absorb water as well as the DOT 3 brake fluid.  

DOT 5 is a silicone-based brake fluid. It will not eat paint or absorb water. It is compatible with all rubber. If water is introduced to the DOT 5 it will puddle in one area and may lead to corrosion in that area. 

DOT 5 fluid is purple and should not be mixed with any DOT 3 or DOT 4 fluids. DOT 5 fluid is difficult to bleed and may require a series of bleeds over time to remove all the air from the system. 

What Sealants are Resistant to Brake Fluids?

Click Image for More Info

Most sealants are resistant to breaking down under modern brake fluids. Permatex is resistant to most automotive fluids and can hold in oily situations.

Permatex has held up over time in certain applications to seal low-pressure brake fluid fittings. It should not be used to repair any leaks in the brake system.

 Any brake fluid leaks will need to be addressed properly to ensure the braking system of your vehicle can function properly. 

To check the current price of Permatex, click here to view the listing on Amazon.

Does Silicone Work With Brake Fluid?

All brake fluid types are not harmful to silicone. If you have a brake leak or happen to spill any type of brake fluid on a silicone seal in your automobile there should be no issue with the brake fluid eating or disintegrating the silicone sealant. 

Silicone sealant should not be used to attempt to fix a leak of brake fluid in your vehicle. The silicone will not be able to form a solid bond with the rubber or metal and will continue to allow the brake fluid to leak over time. 

Is Brake Fluid Harmful to Rubber?

The braking system of your vehicle is full of rubber seals. There are rubber seals on the pistons of the brake calipers as well as the brake master cylinder.

The modern rubber found in these seals can withstand brake fluid without breaking down or disintegrating.

Some factors can lead to the breakdown of these seals. Older and contaminated brake fluid will cause the rubber seals to leak. 

DOT 3 brake fluid is harmful and can break down natural rubber seals found in older vehicles. It should only be used as a temporary fix in these vehicles.

Afterward, the brake system of these vehicles will need to be flushed and replaced with a rubber-safe fluid.  

Will Brake Fluid Eat Tire Rubber? 

Brake fluid will not eat or disintegrate tire rubber. If brake fluid is leaked or spilled onto the tires it should be cleaned up immediately.

It may cause discoloration on the tire but will not cause long-term damage to the tire. 

What Does Brake Fluid Eat Through? 

Glycol-ether-based brake fluid will eat through the paint of your vehicle if it is spilled or leaked on it. It will need to be cleaned to prevent damage. It will also damage any clear coatings found on the rims of your vehicle. 

DOT 5 brake fluid is silicone based and will not harm any painted surface of your vehicle. 

What is the Best Way to Seal a Brake Fluid Leak? 

If there is a leak of brake fluid in your braking system, it will not be able to be sealed and the leak will need to be addressed to ensure that your braking system will continue to operate.

The rubber seals of your brake system will wear out over time and you will need to replace the seals that are working or replace the entire component that houses the seal. 

It is not recommended to use any type of sealant in your vehicle’s braking system. These sealants do not hold for any length of time.

They will continue to allow the brake fluid of your vehicle to leak. You will be at risk of losing too much fluid from your braking system and experiencing a complete failure of the braking system. 

Final Thoughts

There are different types of brake fluid available on the market today, none of which are harmful to silicone or modern rubber parts. The rubber seals found in the braking system are not affected by long-term exposure to brake fluid.

Glycol-ether brake fluids are harmful to paint and painted surfaces. They should be removed immediately to prevent damage to them. Silicone-based brake fluid won’t harm painted surfaces. If there are leaks in your braking system they will not be able to be sealed with silicone or other sealants.

They will need to be addressed and repaired properly to ensure the proper functioning of the braking system of your vehicle. If left unaddressed they can cause a complete failure of the braking system leaving you unable to stop the vehicle.

Automotive Nerd

All of us at Automotive Nerd are passionate about cars. We all specialize in different areas to give you the best possible information on each topic. From car fluids, to engines and tools, we've got it covered.

Recent Posts