Brake Fluid 101: Everything you need to know about brake fluid

Brake Fluid 101: Everything you need to know about brake fluid
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Most vehicle owners are aware that changing the vehicle’s engine oil is one of the most important maintenance services your vehicle needs. While it’s true, and oil does protect your engine from disastrous situations, there are many fluids in your vehicle that serve a very important purpose and keep your vehicle functioning optimally. This includes everything from power steering fluids, coolant, transmission fluid, and brake fluid. Brake fluid is necessary because, without it, you wouldn’t be able to stop your car. Most vehicles today are equipped with hydraulic brake systems, which require fluid to build up pressure and eventually stop your vehicle. Over time though, just like used oil, it begins to break down making its impact lest effective. Here’s everything you need to know about brake fluid and why a brake fluid flush is necessary for your vehicle.

What is the brake fluid?

Brake fluid is an integral part of the hydraulic brake system. Brake pressure forces fluid to the brakes, causing the pads to clamp down on the rotors, attached to the wheel hubs that spin as the wheel turns. The high pressure causes the car to slow down. Without any brake fluid, no pressure can be created to stop the car. Brake systems are completely sealed to assist in creating pressure. If there is a leak in the system, and the vehicle is losing brake fluid, your brakes will not be able to function well, or at all. Brake fluid leaks can be very dangerous and for safety’s sake, it’s best to avoid driving the vehicle until a professional can fully inspect the system.

What affects brake fluid performance?

In short it is moisture. Brake fluid is hydroscopic which means it absorbs moisture from the air. Water in the system can be troublesome, causing the fluid to degrade. Additionally, water has a much lower boiling point than brake fluid. Because there is a tremendous amount of heat created while braking, boiling water in the brake lines can cause your brakes to quit working altogether. That’s why having a brake fluid flush performed regularly is so important. Removing all of the old, contaminated fluid and replacing it with fresh, clean fluid will help to ensure your brakes continue to function properly.

What are the different types of brake fluid?

All forms of brake fluid are given a DOT rating. DOT simply stands for Department of Transport, which sets the safety regulations for the acceptable performance of different brake fluids. The DOT ratings given to brake fluids are based on the liquid’s dry and wet boiling points. As a rule of thumb, the higher the boiling point, the longer the lifespan of the brake fluid.
The table below shows the characteristics of DOT brake fluids:

DOT Dry Boiling Point Wet Boiling Point
DOT 2 190°C 140°C
DOT 3 205°C 140°C
DOT 4 230°C 155°C
DOT 5 260°C 180°C
DOT 5.1 270°C 180°C

Read more about: – Types of Brake Fluid

Can you mix different types of brake fluids?

DOT 4 and DOT 5.1 are both glycol-based brake fluids and are used widely in the automotive industry. Since DOT 4 and 5.1 are both glycol-based brake fluids they are compatible with each other, which means they can be readily mixed without harming your brake system. It is important never to mistake DOT 5.1 (glycol-based) with DOT 5 which is silicone-based and should never be mixed with any other DOT fluid.

Why do you need to change your brake fluid?

Over time, the brake fluid will naturally absorb some moisture, so having them checked and serviced regularly will give you peace of mind that you won’t experience vapor in the brake lines. Moisture in your brake system can also cause rust, which can gum up the little entries in the brake lines or brake equipment, and cause your brakes to malfunction.
Every vehicle has different maintenance needs, however, so you may need to service the brake fluid more or less frequently depending on your annual mileage. Refer to your vehicle’s manual for an advised service schedule.

How often should I change my brake fluid?

There is no set time to change the brake fluid in your vehicle. The timing varies by type of car, the driving conditions you typically encounter, and the manufacturer’s recommendations. But a good rule of thumb is to check it during regular oil changes, and expect to change it every four to five years. Signs that you should get your brake fluid checked immediately include fluid that has a burnt odor, is not clear or transparent, or is at a lower level than it’s supposed to be.

How can I top up my car’s brake fluid?

Step 1: Locate the brake fluid reservoir. The brake fluid reservoir is located in the engine compartment and is mounted on the brake booster against the firewall. The brake fluid reservoir is opaque or white in color.

Step 2: Check the brake fluid level. The fluid reservoir has markings on the side like “FULL” and “LOW”. Use the markings to identify the fluid level inside the reservoir.

Step 3: Top up the brake fluid. Add the brake fluid to the reservoir so that the level reaches the “FULL” marking. Don’t overfill as it could push out past the cap under pressure. Match the brake fluid you need with the fluid type mentioned on the brake fluid reservoir cap. Always use a new, unopened container of brake fluid to fill the reservoir.


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