Do you know what brake fluid is?

Most of us have heard of brake fluid, and we know that it has something to do with the proper functioning of the brakes on our vehicles – but exactly what is it, and why is it so important?

Brake fluid transfers the pressure of your foot on the brake pedal in your car, to the brake pads and discs, thereby slowing or stopping your car. The brake system on your car is made up of a master cylinder, brake hoses and the brake caliper. When you apply pressure to the brake pedal, this pressure is transferred by the master cylinder which compresses or forces the brake fluid along the brake lines, to force the brake caliper to close the disc pads onto the disc rotor. So if you don’t have enough brake fluid in the system, the brakes on your car won’t work as expected.

So, we need to check the levels of the brake fluid on a regular basis, as we are required to do for other aspects of our vehicles such as tyre pressure, oil levels and other fluids. Although the brake fluid is inside a pressurised and sealed system, the brake hoses, seals and fittings are made of rubber which can deteriorate over time. When this happens, you will have small leakage of fluid and you will notice that the brake pedal feels softer and you need to be more aggressive in applying your foot to the pedal in order to stop the car – and eventually as the deterioration worsens and the leakage increases, the brakes may fail entirely.

In addition to the potential for deterioration of the rubber parts within the brake system, there is also the fact that brake fluid breaks down over time and absorbs water, thereby losing its ability to provide the designed level of compression – even though the system is sealed. The brake system of your car generates a lot of heat – and as little as 3.7% of moisture within the brake fluid will reduce the effective boiling point of the brake fluid by almost one third.

You therefore need to replace your brake fluid at least annually, ensuring that you use the brake fluid type as specified in your owner’s manual