How to Check a Vehicle’s Brake Fluid and Lines

What Is Brake Fluid?

Brake fluid is the hydraulic fluid found in all braking systems that allows the transfer of pressure from the brake pedal to be applied to the brake pads and the wheels. When brake fluid is added to a vehicle, the entire system must be pressurized to allow the brake fluid to move throughout the system and facilitate the slowing of the vehicle.

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How To Check Your Car’s Brake Fluid

Brake fluid contains additives to inhibit rust and corrosion of critical brake line components — namely the calipers, steel brake lines, and antilock brake system. While you’re under the hood checking the master cylinder, it’s important to note not only the level but also the quality and pH balance of your car’s brake fluid. This can be a little trickier than merely checking the level. Still, it’s straightforward with a readily available brake fluid test kit purchased from any automotive store or online retailer. With the master cylinder cap still off, follow these two additional steps.

Step 1: Always don disposable plastic gloves to check brake fluid.

Step 2: Open the brake fluid test kit and remove a single disposable strip. Dip the strip into your vehicle’s brake fluid. Shake off any excess. Wait 60 seconds.

Step 3: Compare the color on the strip to the guide/chart included with your brake fluid test kit. This will indicate when and if it’s time to change the brake fluid.


  • Water or debris can cause serious braking system malfunctions if introduced to the brake fluid supply, so proceed with caution.

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  • Do not use DOT5, a high-performance brake fluid, unless directed, as it is not compatible with other brake fluids and can lead to system damage if mixed.

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Know the Warning Signs of Low Brake Fluid

During regular operation, your vehicle should not lose brake fluid. Levels may drop slightly as brakes wear over time. But if the level has fallen significantly since your last fluid level check or full service, it’s time to see a mechanic. Minor issues are much easier and less costly to repair than dealing with total brake failure down the road.

Why is it important?

This tutorial applies to most vehicles, but depending on your specific model, there may be variations that could require additional work or service by a professional.

  • Brake fluid is hygroscopic, meaning it absorbs moisture, including moisture in the air. Don’t leave the reservoir or any bottle of fluid open any longer than necessary. Because it is hygroscopic, the fluid should be flushed every 2 years regardless of color or condition of fluid. This ensures there is no moisture in the fluid to corrode parts internally.

  • Brake fluid is damaging to painted surfaces – even a drop can cause damage. Immediately clean up any spills with a household cleaner or degreaser and a clean rag.

  • If the brake pedal is low or spongy, it’s a good idea to enlist the help of a qualified technician, as those could be signs of a more serious issue.

If you had to add any fluid, you should have the brake system inspected by a qualified professional, such as one of the many available through YourMechanic, who can come to your home or workplace to service your car.

How To Add Brake Fluid To A Vehicle

You are capable of changing out your own brake fluid with enough information and experience. Here are the standard steps to follow when replacing brake fluid. For more detailed information on your vehicle’s recommended brake fluid replacement process please refer to manufacturer information that can be found in your owner’s manual.

Step 1: Park The Vehicle In A Level Location

You want the vehicle to be parked on an even surface to properly read current fluid levels. Park the vehicle in a level area – Make sure the vehicle is stationary and on a level surface.

Step 2: Depress The Brake Pedal

Most Anti- Lock brakes need to be depressed before repairs can be made to them. You should depress the brake pedal about 30 times.

Step 3: Find The Brake Fluid Reservoir Using The Owners Manual

This fluid compartment is typically located under the hood, on the driver’s side of the car. It is typically found against the back of the engine compartment or somewhere around the bottom of the windshield. For exact info on where the brake fluid reservoir is located, check the owner’s manual your car came with.

Step 4: Current Fluid Examination

Like most of the fluid compartments in your car, the brake fluid compartment will be made of a clear plastic that allows you to physically see how much fluid is in the vehicle.

Checking The Volume Of the Brake Fluid

There should also be a maximum and minimum mark on the plastic that shows you what a full brake fluid level looks like. If the level of the brake fluid is below the minimum then the fluid needs to be replaced or topped off.

Checking The Color Of the Brake Fluid

You can determine the integrity of the brake fluid by checking the color. Over time the brake fluid will become compromised and the color will change. Proper braking fluid is generally a light and golden yellow coloration. When the fluid becomes any darker than an amber, it needs to be replaced.

Step 5: Open The Brake Fluid Compartment And Clean

Remove the cap to the brake fluid compartment by unscrewing, or pulling straight up on the car. Different car models will vary in this. Take a rag or paper towel and carefully take away any contaminants like dirt that have accumulated. Disassemble any electrical components that may measure the integrity of the brake fluid, but make sure your battery is turned off first.

Step 6: Adding Brake Fluid

Using a funnel, add the recommended brand of brake fluid to your vehicle. You should continue filling until the volume is just below the maximum fill line. If you are unsure of what fluid to use, your vehicle will recommend one in the owner’s manual. Be sure to use a fluid that is approved by your car manufacturer.

Step 7: Replace The Cap And Sensors

Reinstall the cap to the compartment the same way that it came off.

Step 8: Pump The Brakes

This isn’t just a figure of speech! You HAVE TO pump the brakes to push the fluid back through the system when you have finished. What you are doing is priming the brakes to be ready to stop the car by allowing them to pressurize. You should pump the brakes about 30 times to prime them properly. You should feel the pedal engage.

Signs of Low Brake Fluid

Your vehicle shouldn’t lose brake fluid in normal operation. The level drops only slightly with wear of brakes. So, if the level is down, there’s a chance there’s a leak somewhere. Consult a service professional immediately to have it addressed and avoid possible dangerous reduction in brake performance. Also, your vehicle takes a specific type of brake fluid; typically (but not always), DOT3 or DOT4. In newer vehicles, it will often say right on the brake fluid reservoir cap. If not, consult your vehicle’s owner’s manual.


Note: These instructions are intended as general guidelines. Please consult your owner’s or service manual for specific instructions on changing the oil and filter on your vehicle. Use extreme caution when lifting or jacking any vehicle.

Make Sure to Inspect the Level of Fluid by Following These Steps

Get the right refill for your car

We already mentioned the importance of purchasing the correct refill. Look at the manual or on the lid to find the recommended type for your car. You don’t want to risk making a mistake similar to putting the wrong gas in your car.

Park your car on a flat surface

Your vehicle should be parked on flat terrain to get a real picture. If it is parked on a slope, you can get a wrong reading because the liquid level would be higher on one side. If your vehicle has ABS, you should look at the owner’s manual before doing anything because you might need to depress the pedal.

Raise the hood

Turn off the engine and raise the hood to find the master cylinder. It is usually on the driver’s side, in the back of the engine bay. Some models have a plastic protective panel covering it, so you might have to do a bit of disassembling to get full access to the master cylinder. If you’re having trouble finding it, here’s a tip: consult your owner’s manual.

Open carefully

Cover the fender before opening the tank. If possible, don’t wear your nice clothes because opening a fresh liquid container could damage your clothes and car paint. In case the liquid gets in touch with your hands, wash them thoroughly because if it can strip the paint from the metal, imagine how harmful it could be to your skin.

Clean the cap

Take an old towel or a cloth to wipe the lid before opening it because you don’t want any dirt or debris to fall into the tank once you open it. In case that happened, you’ll notice that the color of the liquid will change over time and even degrade and damage the braking system. So clean it all thoroughly before opening.

Examine the fluid level

In the vast majority of modern cars, the plastic tank is transparent, and there are easily visible MAX and MIN marks on it. As long as the amount of liquid is above the MIN mark, you’re fine.

Inspect the color

Inspecting the tint is another crucial thing to do before actually refiling because it gets contaminated so easily. When it is clear, the shade is lightly golden, like tea, but it gets darker when dirty with a bit of an amber undertone. Do a dip test with a strip, if it is dark, or you can see some debris floating around, there’s no point in refilling because your car needs a flush. Contact your mechanic to drain the system.

Refill time

In case the amount of liquid is under the MIN mark, and the color is looking good, there are no specks of dirt floating, then it is time for a refill. You should fill it up just a bit under the MAX mark. There’s no need to overfill it because it could spill out and cause damage. You might need to use a small funnel for refilling.

Cleaning again

Now carefully wipe the inside of the cap, so it is spotless before you put it back on. Press it down until it falls into its place, and ensure it is well sealed.

Test drive

After all that hard work is done, it is now time for a test drive to ensure everything is still running the way it should. Go for a spin around your neighborhood; there’s no need to go crazy on an open road like in TV car shows. Once you’re back, inspect the tank again to ensure there’s no leaking and that everything is done correctly.

How to add brake fluid

If you have determined that you do in fact need to add brake fluid, then you should follow these next two steps.Purchase the proper sort of fluid. Each vehicle requires a different sort of fluid, so consult your owner’s manual to learn what type of brake fluid your car needs.This is not simply a matter of generic vs. brand-name fluid, but the actual specification of brake fluid itself. DOT 3, DOT 4, and DOT 5 are the different types of brake fluid, and cars are made to receive one of them and not the others. Make sure you've acquired the right brake fluid, or you could end up causing damage. Pour fluid into the reservoir. Once you’ve acquired the proper fluid, pour it into the reservoir until it returns to the range between "max" and "min." Don’t go past the "max" line.If you are constantly having to add brake fluid, you may have a lingering brake issue that a professional needs to check out.MORE: Mechanical breakdown insurance vs extended warrantyFind insurance savings (100% Free)

Can You Just Add Brake Fluid to Your Car?

Simply said, yes. Although you can take your car to an experienced mechanic to do it for you, this is something you can do on your own without too much hassle. Whether you own some of the most expensive cars in the world or you just bought a used car, the process is quite the same and straightforward.

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