• Home
  • Quick Order
  • 0 items (£0.00)

Selecting the Right Brake Fluid

Brake Fluid

It's often an over looked area in performance/race car set-up but choosing the right brake fluid can be critical in getting the most out of your brake system. Here we look at some of the fluids available on the market and the different applications they are suitable for.

Expensive is Best?

A common held belief is that the most expensive brake fluids are the best ones for all circumstances. People will often put a high end brake fluid such as SRF into a normal road car thinking that because it's expensive it must offer better performance. Brake fluids like SRF do offer a performance advantage but only in certain circumstances. Don't fall for this trap, it's easily done but using a brake fluid which is 'to highly spec'ed' can be just as bad as selecting one which is to low a specification.

Criteria for Brake Fluid

In most cases there are two criteria which you should look at when selecting brake fluid.

Firstly the substance which makes up the brake fluid. This is usually either glycol based or silicon based. It is important to check which type you should use and these should never be mixed (either check the car's handbook or check with the brake components manufacturer(s)).

The second criteria is the boiling point. This is the temperature at which the brake fluid will start to boil and loose it's effectiveness. However brake fluid does need some temperature in order to become more effective. The higher the boiling point the higher this optimal temperature is. The temperature of the fluid is determined by how hard the fluid is having to work, high brake pedal pressure and high speed will create more temperature then gentle driving. The boiling points for brake fluid are usually specified as 2 numbers, the dry boiling point and the wet boiling point. Dry boiling point is for fresh/clean brake fluid which hasn't been used. Over time the brake fluid becomes contaminated with water, this reduces the boiling point to the wet boiling point. Dry is clean fresh fluid, wet is older contaminated fluid. Wet boiling point is more critical when your application makes it difficult to change the brake fluid regularly.

So Which Brake Fluid Should You Use?

Below is a suggested application list for brake fluids. This is only a starting point but for most applications it will be correct:

Application Example Brake Fluid
Road / Fast Road AP DOT5.1
Performance / Trackday AP DOT5.1, AP R1,
General Motorsport AP R2, AP R3, Millers 300
High Level Motorsport (F3, GT, LMP3 or higher) AP R4, Castrol SRF, Endless RF-650


Getting the Most out of Your Brake Fluid

To get the best performance out of your brake fluid remember:

  • Select a brake fluid which is suitable for your application
  • Change regularly, especially if there's a high chance of contamination
  • Store with an unbroken seal, in a dry environment