Why is brake fluid change important for a car’s operation?

1. What is the brake fluid?

To know the importance of the brake fluid, first of all, we need to break down the function of the brake fluid in the braking system. Automobiles which uses the hydraulic brake would need brake fluid as a hydraulic liquid. In a hydraulic braking system, with the incompressible nature, brake fluid could play as the means of delivering the braking force. Specifically, when you press the brake pedals, the force you create is transferred and amplified to four brake rotors in four wheels through the brake fluid, and stop the vehicle. As you can see, the brake fluid play a crucial part in the function of the braking system, and there is the requirement for an instant effect.

Brake fluid is an important part of the braking system

2. What is good brake fluid?

• Firstly, efficient brake fluid remains a stable viscosity even when the temperature changes, for example, when the temperature drops or increases.

• Besides, the good brake fluid should have a high boiling temperature. As the braking system is exposed to the high-temperature condition so that the fluid will not vaporize when the system gets heated. Unlike the liquor, steam has a high compressibility, which will make the fluid unable to transfer the force into the braking rotor effectively, hence, the car is unable to stop.

• Thirdly, brake fluid should not have the corrosion effect on the metals that it exposes to, for example, calipers, wheel, cylinders, and ABS control valves.

• Last but not least, brake fluid should have a consistently low level of compressibility. If the brake fluid becomes more compressible, a large pedal force is required to attain the same brake pressure. It will drastically reduce the effectiveness of the brake system.

3. How to know it's time to change the brake fluid?

It is recommended that you should change the brake fluid every two years or every 30,000 miles. For cars with feature like ABS with ESP and traction control, the brake fluid is expected to be changed more frequently. However, there are also some certain signs indicating that it is the time for brake fluid replacement.

For example, to stop the car, you have to press the brake pedal really hard. Or if the car takes more than one push the pedals more than multiple times to hold back the car.

On the following clips, you can see the signs of poor brake fluid:

How to check brake fluid

4. Why do I have to change brake fluid?

Brake fluid could absorb moisture, which could make the fluid lose it compressibility and lower the boiling point. Hence, it will become less effective. The water content should not be higher than 3%. Above that point, the brake fluid needs to be changed. Or if the brake doesn’t give the same responsiveness as before, you should get it checked by mechanics. Don’t wait until the braking system loses all the power and cause disastrous brake failure.

If you delay brake fluid change, you might have to face the risk of ruining some expensive part of the car as brake fluid with high water content could corrode the other braking components.

Beside regular brake fluid flushing, you can also have brake fluid bleeding, which involves removing all the air bubbles in the lines.

Brake fluid needs to be changed periodically

Even though brake fluid is closely associated with the braking system – one of the most important parts of a car, it doesn’t receive an equivalent attention from the car owner. Many of the drivers usually miss out the periodical brake fluid changes for their car. The next time you visit the maintenance station, make sure that you will have the mechanic to check your brake fluid.

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