Although brake fluid is one of the most important components of your vehicle’s braking system, it is often overlooked and neglected. It needs to be changed periodically, yet many drivers don’t even know how to check it, let alone replace it.
Shop For Car Brake/Clutch Fluid
Shop For Motorcycle Brake/Clutch Fluid
We have a variety of different brake and clutch fluids on offer. To learn more about what brake fluid is, how it works, and how to change it, read on.
Brake fluid, also known as clutch or hydraulic fluid, is responsible for moving component parts within your braking system. When the brake pedal is pressed, the compressive effect builds pressure, forcing the fluid to press down on the rotors. This will then squeeze the brake pads in order to bring your car to a stop.
Braking is a high-stress, high-friction system. Because of this, you must be able to rely on your braking fluid operating properly at high pressures and temperatures. It’s vital to check your brake fluid regularly to ensure that your braking system will perform perfectly no matter the conditions.
brake lines, leading to a soft-feeling pedal. Subsequently, this will stop your car braking as well as it should.
Because of this potential for contamination, you need to change your brake fluid either every two years, or every 24,000 miles – whichever comes first. This will help your brakes to continue working properly, and whilst it isn’t an easy task it is one you can do at home.
Changing brake fluid is a simple, three-step process.
Every kind of brake fluid is given a DOT rating, which will classify the specifications of the fluid. This is assigned by the Department of Transportation who sets the safety regulations for the acceptable performance for different brake fluids.
The DOT ratings given to brake fluids are based on the liquid’s dry and wet boiling points. The dry boiling point refers to the boiling point of the fresh fluid, and the wet boiling point means the boiling point of a fluid which as absorbed moisture. Generally, the higher the boiling point, the longer the brake fluid will last.
There are two main types of brake fluids:
Glycol based DOT 4 fluid is the current mainstream brake fluid, and you will see that the specification is considerably better than DOT 3 which it replaces.
DOT 5.1 has higher specification still and is for fast road and occasional track day use. It has a similar spec to DOT4 for the boiling point (>260) but is a lot lower viscosity @-40C typically 900 centistokes (compared to 1500 - 1800 centistokes for DOT 4 and super DOT 4).
Silicone based DOT 5 was originally introduced to give higher temperature performance over glycol DOT 4. Silicone fluid also has other advantages; it does not damage paintwork and it does not absorb water.
However, silicone fluid is a poor lubricant and does not lubricate ABS pumps as well as PAG fluids. It is also more compressible than PAG fluids, which can result in a sluggish or spongy pedal.
It therefore requires special design considerations in braking systems. Furthermore, because it does not absorb water, any water remains as globules, which can pool in low spots in the system and cause corrosion. This water can vaporise when heated under heavy braking giving a disastrous effect on braking efficiency.
Listed below are the minimum dry/wet boiling point specifications for each DOT level.
You can use our parts finder to find the right brake fluid for your car or van.