Comparing Motorsports Brake Fluids

Most road cars will benefit or outright require a few tweaks before they can be safely and consistently enjoyed on high performance environments like track days.

A more agressive wheel alignment with increased negative camber, improved cooling, and motorsports brake pads and brake fluid are the most common items in the checklist to get a road car ready for track days.

Factory brake fluids for cars are not designed for high performance driving and can easily degrade after a a couple laps around a circuit. During heavy braking, heat is transferred from the brake discs and pads into the calipers and from the calipers onto the brake fluid. When brake fluid gets too hot, it can start to boil and air bubbles form, causing the fluid to progressively lose its properties and ultimately resulting in a dangerously soft brake pedal feel. A significant loss of braking torque will make it difficult for the driver to stop the car.

No matter if you are driving a pure race car (imagine a Cayman GT4 Clubsport) or a dual duty road car, you should be using a motorsports grade brake fluid if you plan to do more than a couple laps around a circuit.

Here is a quick summary and comparison of the most commonly available motorsports brake fluids in Europe:

Brand Fluid Cost per Bottle Cost per Liter Wet Boil Point Dry Boil Point Ventisca Rating
Motul RBF 600 14 € 28 € 401 594
Motul RBF 660 16 € 32 € 400 617 ⭐⭐⭐
Endless RF 650 60 € 120  424 622
Castrol React SRF 65 € 65  518 608

* Prices are average online prices as of April 2022.

Motul RBF600 & Motul RBF660

The RBF line by Motul is a commonly availailable, budget friendly staple brake fluid suitable for beginners or cars spiritedly driven that see at most 1 or 2 days of light race track duty per year.

The 660 provides a small boost in brake pedal stiffness feel through lower compressibility and a small bump in dry boiling point as well. It is usually well worth the premium over the standard 600.

Advanced drivers and / or cars with modern high performance tires will find this brake fluid not completely adequate for continuous lapping. They will find the pedal feel degrades throughout an event and will want to bleed their fluid before their next race or track day. At 30 EUR a bottle however, this might be acceptable specially if you are able to perform your own fluid changes.

Endless RF 660

The Japanese king of rock solid brake pedal feel, lap after lap, thanks to its extremely low compressibility properties. Good range of wet and dry boiling points and lower hygroscopicity (tendency to absorb water moisture in the environment) than other leading fluids.

Its main downside is its spotty availability in Europe and its price of well over 100 EUR per liter.

Castrol SRF

Our overall favorite brake fluid considering its balance of performance, price and availability, although we wish it was available in 0.5 L bottles as well, for those seasonal or mid year brake bleeds.

An overall great performer, it boasts one of the highest wet boiling points for brake fluids. Although it might not offer such a consinstently stiff pedal feel as the Endless RF650 and can lose a bit of feel during an event, it always recovers well after some cool down and does not require bleeding or complete flushing of the brake system often. 

Motorsports Brake Fluid Maintenance Intervals

Besides cost per liter, the only other downside of DOT 4 motorsports brake fluids compared to OEM or factory equivalents is their higher hygroscopicity. That means that they tend to absorb water moisture at a slighty higher rate than factory fluids, and will require bleeding intervals a bit more often. We recommend you bleed your brake system at least once per season -even if the brake pedal still feels ok, the boiling point of the fluid will decrease over time as it asorbs moisture.

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