High-Performance Brake Fluids

The first item to upgrade is brake fluid. No matter what brake fluid you use, you need to change the brake fluid at LEAST every year. We strongly recommend the system is flushed once per year to prevent internal caliper corrosion and remove the old fluid that has absorbed moisture, thus significantly lowering its boiling point. All non-silicone brake fluids are hygroscopic by nature. This means that the fluid will slowly absorb moisture over time and the dissolved water in the fluid boils at 100 deg C, lowering the system’s boiling point drastically. In fact, one to two good hard stops with old fluid can boil the system instantly, causing the pedal to sink to the floor while you are trying to get stopped!

Brake fluid is relatively inexpensive so change it once a year. Your calipers and its internal parts will last a lot longer if the fluid is kept clean and dry.

There are several choices for good brake fluid. We have listed the most popular ones and their physical characteristics as related to braking performance. The most relevant number to compare is the wet boiling point. This tells you something about the fluid’s affinity for water. The lower the wet boiling temperature, the more moisture fluid will absorb. True racing-type brake fluids are quite expensive but will give a massive improvement in pedal feel and resistance to brake fade compared to traditional DOT 3, 4, and 5 brake fluids.

Lots of people ask about what DOT 3, DOT 4, and DOT 5 really mean. These are a set of specifications about dry and wet boiling points for each grade of brake fluid. As you will see, this is a guideline only. You must read the specification on the product’s container. All brake fluid should be purchased in small cans, and if not used immediately, discarded. Once the seal on the container is broken, the contents start to absorb moisture.

 
Dry Boiling Point/deg C
Wet Boiling Point/deg C
DOT-3
205
140
DOT-4
230
155
DOT-5
260
180

Now, for comparison, here are the specifications for some of the most popular high-performance brake fluids in use.

 
Dry Boiling Point/deg C
Wet Boiling Point/deg C
Castrol SRF
310
270
Motul RBF 600
312
216
Motul Racing 600
307
216
AP Racing 600
300
210
Ate Super Blue
280
200
Valvoline
267
167
Castrol LMA
230
155
Wilwwod 570
299
140
PFC Z-Rated
288
140
AP Racing 550
277
127

Quite a variation! Before you make any fluid purchases you should know a few things. AP 600 is not compatible with any other fluid. It was formulated for F1 and other cars using carbon-carbon brake components that will see temperatures of over 500 deg/C. Castrol SRF, another very fine product, will set you back about $73 per liter while Ate Super Blue brake fluids can be purchased for about £19.50 per litre. Motul and Ate brake fluids will perform quite well when changed every 6 months. Under certain circumstances of track conditions, vehicle weight, brake swept area, and engine horsepower, you will require the use of a super-duty fluid such as the Castrol SRF. You should also be sure that the brake fluid that you decide to use is compatible with what you currently are using. Check with the brake fluid’s manufacturer to be sure!

We use and recommend Castrol SRF for all performance brake applications