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Brake Fluid: Ultimate Guide on Everything You Need to Know!

  • Car Care Tips
  • Renee Martin
  • 8 minutes

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You step on the brakes, and just like that, your car stops. That’s how brakes are supposed to work, with everything in perfect symphony. But, for your brake system to work properly, it needs brake fluid. It’s your car’s most vital fluid but also probably the most overlooked. So, here’s all you need to know about brake fluid, how to check it, how to change it, and how often you need to change it.

It’s quite simple, actually. You need brake fluid for your brakes to work. This is because it’s a hydraulic system. Pressure on your brakes¬†forces fluid down to your brakes. This, in turn, pushes the brake pads onto the rotor. The rotors are connected to the hubs of the wheels and spin when the wheels turn. When there is more pressure on the car, it slows down. No fluid means no pressure. You also have an emergency brake, which is also called a parking brake. But it’s not necessarily strong enough to stop the car in an emergency. So it’s a big deal if you or your mechanic finds a brake fluid leak. You should fix it right away, and until it’s fixed, you shouldn’t drive it.

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What is brake fluid?

Brake fluid is the hydraulic liquid that powers your car’s brakes. Without it, your vehicle won’t stop in time. It transmits the pressure you exert on the brake pedal through the numerous brake lines to the brake calipers and (if equipped) brake drums, which work to slow down your car.


Is brake fluid flammable?

Brake fluid is flammable, but it is not volatile. This means it’s quite unlikely that brake fluid will cause a fire, but it can probably feed a fire that’s already started.

How to check brake fluid

You may test the brake fluid by removing the master cylinder lid and dipping a strip into it. After shaking off the extra fluid, let 60 seconds pass before checking the strip’s color against the reference provided on the brake fluid testing packaging.

Here are detailed steps on how to check your vehicle’s brake fluid:

Let your car cool down

If you are back just after a ride, let the vehicle cool. The components under the hood could be hot after the ride. Therefore, allow the components to cool down to save yourself from burns and injuries during the process.

Open up the hood

Next, open the hood up and locate the brake fluid reservoir. In most vehicles, the reservoir is towards the back of the engine on the driver’s side. However, this can change based on your vehicle, make, and year. So, if you have trouble locating the reservoir in your vehicle, refer to the owner’s manual.

Check fluid levels

After locating the reservoir, it’s time to check the fluid level. Check the fluid level using the marking on the side of the tank. You have no problem if the fluid is anywhere between the max and min line. But, if you notice the fluid below the minimum level marking, it’s time to top up the fluid.

Also read: How Much Brake Fluid Does a Car Really Need?

What color is brake fluid?

Brake fluid that’s in good condition should be practically clear with a slight yellow tint. It should be similar to the color it was in the container when you put it in your car’s reservoir for the first time.

Over time, the color of brake fluid fades to gray or brown. This happens due to constant heating, deteriorating rubber brake lines, moisture, and age.

When to change brake fluid

Car care experts recommend brake fluid flushes every 30,000 miles or two years. However, this can change depending on how often and how much you drive. Also, if you notice the car exhibiting signs of low brake fluid, get it checked immediately.

The best thing to do is make checking/adding your brake fluid a part of your car maintenance checklist.

How to change brake fluid

If you decide to change your own brake fluid, follow these steps:

  1. Remove the used and contaminated fluid from the master cylinder reservoir using an inexpensive turkey baster.
  2. Wipe out the reservoir with a lint-free cloth, if you are able to get in there.
  3. Refill with new fluid until it reaches the ‘full’ line and then replace the reservoir cap.

The fresh fluid forces the old fluid out of the system when you bleed the brakes (remove air from the braking system). Continue to bleed the brakes until clean, clear fluid emerges through the bleeder screw.

What is brake fluid flush?

A brake fluid flush is when you completely replace your brake fluid. It entails cleansing the braking system and refilling the master cylinder with new fluid. We suggest that drivers get their brakes cleaned every two to three years to ensure that their brakes are properly maintained.

Is a brake fluid flush really necessary?

Yes, it is absolutely necessary. That’s because when you brake, heat is produced, which breaks down your brake fluid and wears it down. This process leaves behind moisture, which can lead to rust on your brakes. In addition, over time, the solution can become contaminated by dirt, rubber, and metal. If these problems aren’t fixed, they can cause the brakes to work less well and eventually fail.

Also read: Know All about Squeaky Car Brakes!

What does the DOT Rating on brake fluid mean?

A DOT rating is assigned to all types of brake fluid. DOT is an abbreviation for the Department of Transportation, which establishes safety standards for the acceptable performance of various braking fluids. Brake fluids are awarded DOT ratings based on their dry and wet boiling points. As a general rule, the higher the boiling point, the longer its lifespan.

What’s the difference between DOT 3 and DOT 4 brake fluid?

Both DOT 3 and DOT 4 brake fluids are glycol-based. The main difference between the two is that DOT 3 brake fluid absorbs less water from the air than DOT 4 over time. Therefore it requires fewer frequent fluid changes. Because DOT 4 brake fluid has greater dry and wet boiling points, it is suitable for use in higher temperatures.

Is it okay to mix DOT 3 and DOT 4 brake fluid?

The boiling point of DOT 4 is higher than that of DOT 3. You can substitute DOT 4 for DOT 3 in any situation, but you must never do the reverse. If you use DOT 3 in a DOT 4 brake, you run the danger of boiling the brake fluid.

What is DOT 5 brake fluid used for?

DOT 5 is typically used in classic vehicles that are stored for lengthy periods of time and require a water-resistant braking fluid. DOT 5 is silicon-based. Therefore, it has the advantage of not absorbing water and hence not corroding braking systems. It does not, however, work well with ABS brakes.

Does it matter what brake fluid I use?

It is best to use the fluid specified by your original vehicle manufacturers.

How to recycle brake fluid

If your brake fluid is uncontaminated (not used or mixed with toxic solvents in your car), you can recycle it. The best thing to do is seal it in a jar and take it to a nearby recycling facility that will repurpose it for future use.

How to dispose of brake fluid

Never throw brake fluid into a sink, storm drain, sewage systems, or on the ground. Old brake fluid removed from automobiles or trucks is classified as hazardous waste. You must take it to a treatment facility for appropriate and legal disposal.

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How to dispose of brake fluid at home

Small amounts of brake fluid don’t necessarily require a trip to a disposal facility. It can be absorbed and thrown away in 3 easy steps with kitty litter, a bucket, and a sealable garbage bag.

1. Pour the fluid into a clean kitty litter pan

Any pan that’s 9 X 12 inches in size will do. You may also use the metal pan you might use to capture automotive fluid when working on your car. If you don’t already have kitty litter, you can buy it online or from a pet store. Pour the fluid on top of the cat litter and ensure it’s out of reach for your dogs and youngsters because it can be harmful if consumed. Also, because it is flammable, keep it away from flames and other heat sources.

2. Leave the container alone for 3 to 4 days

Because the fluid is alcohol-based, the alcohol will evaporate over time and is absorbed by the kitty litter. So if you shake the pan and still see some fluid, leave it alone for a few more days until all of the liquid has evaporated.

3. Dispose of the kitty litter

Once there are no signs of brake fluid in the kitty litter, place it in a garbage bag, firmly wrap it, and dispose of it as you would the rest of your trash.

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