Brake Fluid change & replacement made easy

How does brake fluid work?

Brake fluid is a special liquid in your car’s braking system that helps transfer the force you apply when pressing the brake pedal. When you press the brake pedal, the fluid moves through the brake lines, transferring that force to the brake calipers (in disc brakes) or wheel cylinders (in drum brakes), which then press the brake pads or shoes against the discs or drums. This creates friction, slowing down or stopping your car.

The brake fluid allows the brake system to function as a hydraulic system, meaning it transfers pressure evenly and efficiently from the pedal to the brakes. This gives you a firm and responsive brake pedal feel.

Brake fluid is designed to work under high pressure and extreme temperatures, but over time it absorbs moisture from the air—a property known as being hygroscopic. This moisture lowers the fluid’s boiling point, which can reduce braking performance and increase the risk of brake fade (where the brakes stop working effectively when hot). Contaminated fluid can also cause corrosion in the braking system.

To keep your brakes working safely and efficiently, it’s important to change the brake fluid regularly—usually every 2 years, or as recommended by your car’s manufacturer.

What does a brake fluid change job involve?

Over time, brake fluid can degrade or become contaminated, which can affect the performance of your brakes. Regular brake fluid changes help maintain safe and effective braking. Here’s a look at what happens during a brake fluid change:

• The mechanic begins by ensuring the car is safely parked on a level surface, with the engine off and the parking brake engaged.

• The mechanic inspects the entire brake system, checking for any signs of wear or damage that might need attention.

• The mechanic drains the old brake fluid and replaces it with fresh fluid, ensuring it meets the manufacturer’s specifications for your vehicle.

• The mechanic will bleed the brake system to remove any air trapped in the brake lines, ensuring the system functions properly.

• Once the fluid has been replaced and the system is bled, the mechanic will test the brakes to make sure they are working as expected and verify the brake fluid level.

• The job is finished by ensuring everything is secure and the brake fluid is at the proper level, ensuring your car’s braking system is in top condition.

How do I check brake fluid?

Checking your brake fluid is pretty quick and easy, and it can help you spot potential problems before they get serious.

Here’s how to do it:

• Pop the bonnet – Look for the brake fluid reservoir. It’s usually near the back of the engine bay, on the driver’s side, and has a labelled cap that says “brake fluid.”
• Check the level – The reservoir is usually made of clear plastic with “MIN” and “MAX” lines on the side. You should be able to see the fluid level without opening the cap. If it’s between the two lines, you’re good to go. If it’s close to or below “MIN,” it’s time to top it up or get it checked.
• Look at the colour – Brake fluid should be a clear, light yellow. If it looks dark brown or dirty, it might be old and need changing.
• Top up if needed – If the level is low, you can carefully add the correct type of brake fluid (check your car’s manual). Don’t overfill, and make sure no dirt gets into the reservoir. Also, avoid spilling it—brake fluid can damage paint.

If your brake fluid is low, it could mean there’s a leak or your brake pads are worn down. It’s best to get a mechanic to take a look, especially if you’ve noticed any changes in braking performance. A car brake inspection will help identify issues.

What causes cloudy brake fluid?

Cloudy or murky brake fluid is usually a sign that it’s old or contaminated and here's why it could happen:

• Moisture absorption – Brake fluid is hygroscopic, which means it naturally absorbs moisture from the air over time. Too much moisture can make the fluid look cloudy and lower its boiling point, which affects braking performance.
• Dirt or debris – If the reservoir cap isn’t sealed properly or dirt gets in during a top-up, it can contaminate the fluid and make it look cloudy or dirty.
• Rust or corrosion – Moisture in the system can cause internal parts, like brake lines or cylinders, to rust. Tiny rust particles then mix with the fluid, changing its appearance.

If you notice your brake fluid is cloudy, dark, or doesn’t look quite right, it’s a good idea to get it checked and possibly replaced. Fresh brake fluid should be clear with a slight yellow tint, anything else could mean your braking system needs some attention.

How do I know if I need a brake fluid change?

Here are some signs that it may be time for a brake fluid change:

• Reduced Braking Performance – If your brakes feel less responsive or require more pressure to stop the car, the brake fluid could be degraded.
• ABS Warning Light – If your Anti-lock Braking System (ABS) light comes on, it could indicate an issue with the brake fluid or the braking system itself.
• Spongy or Soft Brake Pedal – A brake pedal that feels unusually soft or takes longer to engage could be a sign of moisture or air in the brake fluid.
• Unusual Noises When Braking – Squealing, grinding, or other noises when you press the brake pedal could signal brake fluid issues or worn-out brake components.

If you suspect there is any issue with your brake fluid or are concerned about its age or condition, book an inspection ASAP.

Is brake fluid flammable?

Yes, brake fluid is flammable, but only at high temperatures. While it’s not likely to catch fire under normal conditions, it can ignite if it leaks onto hot engine parts or during a fire. If you notice any signs of a brake fluid leak, like a puddle under your car, a soft brake pedal, or even a warning light—it’s important to get it checked as soon as possible. Leaks can be dangerous and affect your car’s ability to stop safely!

What happens if my brake fluid is low?

If brake fluid is low, your car’s braking system won’t work as it should. You might notice the brake pedal feels soft or spongy, it takes longer to stop, or a warning light appears on the dashboard. Low fluid can also let air into the brake lines, reducing braking power and, in more serious cases, causing complete brake failure. It’s important to top it up with the correct fluid and get a mechanic to check for leaks or worn components ASAP.

How often do I need a brake fluid change?

It is recommended to change your brake fluid every 24 months or 24,000 miles, whichever comes first. If you fail to do so, it may cause your brakes to fail, making the car unsafe to drive.

Is brake fluid change included in a service?

Generally, yes it will be included in a service. With ClickMechanic, a top-up for brake fluid is included in all 3 types of service - interim, full and major service.

How much does a brake fluid change cost?

A brake fluid change typically costs around £95, though prices can vary between £80 and £120. The final cost depends on factors such as your location, vehicle type, and the specific parts recommended by your car’s manufacturer. Find out what you could save by having your brake fluid changed by ClickMechanic by entering your car reg and postcode.

What does a ClickMechanic brake fluid change quote cover?

Unless otherwise stated, the quote will cover:

• The cost of the brake fluid
• The mechanic's labour for replacing the fluid and bleeding the system
• VAT (if applicable)
• 12 months parts and labour warranty

Can the brake fluid be changed by a mobile mechanic?

Yes, absolutely — a mobile mechanic can change your brake fluid. It’s a fairly straightforward job that doesn’t require a garage setup, so it’s perfect for a mobile visit.