How to Check Brake Fluid: Guide to Checking Essential Car Fluids

Most of us don’t think about car fluids until a dashboard light starts flashing. But here’s a secret from your local mechanics: a few minutes of checking your fluids today can save you thousands of pounds in repairs tomorrow.

You don’t need to be an expert to keep your vehicle running smoothly. Here is everything you need to know about the lifeblood of your car.

What Fluids Does a Car Actually Need?

Your car is a complex machine that relies on various liquids found in the car’s engine bay to lubricate, cool, and provide pressure to different systems. The “Big Four” you should keep an eye on are:

1. Engine Oil: Lubricates moving parts.
2. Coolant (Antifreeze): Prevents your engine from overheating. The cooling system circulates coolant to maintain proper engine temperature and prevent overheating, so it’s important to check and top up coolant as needed.
3. Brake Fluid: This liquid transfers the force from pressing the brake pedal through the brake fluid to the brakes, allowing your car to slow down or stop safely. 
4. Power Steering Fluid: Makes it easy to turn the wheel.

Most manufacturers recommend a full flush and replacement of brake fluid every 1-2 years or every 24,000 to 30,000 miles. 

Locating the Brake Fluid Reservoir

Before you can check your brake fluid, you’ll need to find the brake fluid reservoir in your car’s engine bay. Start by popping the bonnet and looking towards the rear of the engine compartment, usually on the driver’s side, but sometimes on the passenger’s side depending on your vehicle. The brake fluid reservoir is typically a semi-translucent container, often with a black screw-on reservoir cap marked by a yellow symbol (like a circle with brackets or an octagon).

To get an accurate reading, make sure your car is parked on a flat surface and the engine is off and cool. This ensures the fluid level is stable, and you can safely check your brake fluid. Look for the minimum and maximum markers on the side of the reservoir; your brake fluid level should sit between these lines. If the container is dirty, wipe it down with a clean cloth so you can clearly see the fluid level inside.

Always check the reservoir cap for a label indicating the correct brake fluid type for your braking system. Using the wrong brake fluid can lead to serious issues, including brake failure, so double-check your vehicle manual or the cap itself before topping up. The right brake fluid is crucial for keeping your brakes responsive, especially under high temperatures and heavy use.

Power Steering Fluid Check

While you’re under the bonnet, you might also notice the power steering fluid reservoir nearby. This is another essential fluid reservoir, usually with its own dipstick and markings for hot and cold fluid levels.

If you’re ever unsure about the location of the brake fluid reservoir, the correct brake fluid to use, or how to check your brake fluid level, your vehicle manual is your best resource. And if you’re not comfortable doing the job yourself, don’t hesitate to visit a local garage. Keeping your brake fluid at the right level is essential for your safety on the road.

How to Check Your Brake Fluid

Your brakes are your car’s most important safety feature. Unlike engine oil, which gets “used up,” your brake fluid level shouldn’t drop significantly unless there is a leak or your brake pads are wearing down.

How to check it: A step-by-step guide

• Check the Levels: Most reservoirs have “Minimum” and “Maximum” lines printed on the side. The fluid should be at the correct level, between these markers. Never fill past the maximum marker, as overfilling can cause issues like water absorption and reduced braking performance. If the fluid is below the minimum mark, it needs to be topped up immediately.
• Look at the Colour: Healthy brake fluid is clear or pale golden. New brake fluid should be clear or light amber. If it looks dark brown, black, cloudy, or has black “flecks” in it, it’s contaminated and needs to be replaced. Contaminated brake fluid can cause the brakes to become less effective.
• Top Up if Needed: If you need to refill or fill the reservoir, use a funnel to avoid spillage and ensure accuracy. Only use the recommended type of brake fluid for your vehicle. Be careful not to spill brake fluid on your vehicle’s paint, as it can corrode paintwork. If any brake fluid is spilt, clean it immediately with plenty of water to prevent damage. After topping up, ensure the reservoir cap is securely closed to prevent leakage or contamination. If you are unsure about how to refill your brake fluid, do not attempt it yourself; seek professional help.
• Check for Leaks and Pedal Feel: If you check the level soon after topping up and it is still low, you may have a leak in the brake system. Visible fluid leaks on the ground near the wheels indicate a dangerous brake fluid leak. If the brake fluid level is consistently low, it may indicate a leak or worn brake pads, requiring professional inspection. If you have to top up your brake fluid regularly, it could indicate a leak in the braking system. A spongy or soft brake pedal can mean air or moisture in the brake lines, compromising braking effectiveness.

Pro Tip: Never leave the brake fluid reservoir cap off for long. Brake fluid absorbs moisture from the air, which can lower its boiling point and make your brakes feel “mushy.” Brake fluid performance can also be affected by heat and temperature; high temperatures can cause brake fluid to boil or degrade, reducing braking effectiveness.

How to Check Your Power Steering Fluid

Does your steering wheel feel heavy or make a whining noise when you turn? It might be low on power steering fluid.

How to check it:

• Find the Cap: Look for a small reservoir with a steering wheel icon or “Power Steering” written on the cap.
• Use the Dipstick: Many power steering caps have a small dipstick attached to the underside. Wipe it clean, screw it back on, pull it out again, and see where the fluid sits.
• Check the Reservoir: Some modern cars use a translucent tank (like the brake fluid). Simply look at the level against the “Hot” or “Cold” markings or the correct line on the side of the reservoir.

When Should You See a Professional?

Checking your fluids is easy, but topping them up can be tricky. Using the wrong type of fluid (like putting DOT 3 brake fluid in a car that requires DOT 4) can actually damage your system.

If you notice any of the following, it’s time to bring it to the experts. 

• The brake fluid is running low frequently; this is a sign of a potential problem, such as a leak or worn brake pads.
• The fluid levels are consistently dropping (this indicates a leak).
• The fluid looks dark, cloudy, or burnt.
• The “Brake” or “ABS” warning light is on.

A consistently low brake fluid level is a sign that there may be a leak or worn brake pads, both of which require professional inspection. After topping up, always test the brake fluid level again to ensure it is correct.

Is your car due for a service or check-up? Don’t wait for a breakdown to find out your fluids are low. Stop by our garage for a quick fluid level inspection and peace of mind!