Why Brake Fluid Choice Matters

When upgrading your brakes, most people jump straight to discs and pads—but your brake fluid plays an equally crucial role. Whether you’re driving spiritedly on the road, attending occasional track days, or racing competitively, the right brake fluid can make or break your braking performance.

Carbonwurks was built from a Motorsport heritage with Daniel the owner being involved with racing in the form of Formula 2, Formula 3 and racing for prestigious brands such as Aston Martin and Ferrari. In this guide, we’ll break down the differences between the most popular performance brake fluids from MOTUL: RBF 600, RBF 660, and RBF 700, and help you choose the best one for your setup.

What Does Brake Fluid Actually Do?

Brake fluid is a hydraulic fluid that transmits force from your brake pedal to the calipers. It also absorbs heat generated by friction at the pads and discs. The more aggressively you brake, the more heat is generated—especially on track.

If your fluid overheats, it can boil, causing vapour lock, a soft pedal, or complete brake fade. That’s why high-performance brake fluids are designed with higher boiling points to resist fade under extreme temperatures.

Understanding Boiling Points: Dry vs Wet

• Dry Boiling Point: When fluid is fresh and moisture-free. This is the maximum thermal performance.

• Wet Boiling Point: After the fluid has absorbed some moisture over time (which it naturally does). This reflects real-world conditions.

Hygroscopic fluids like MOTUL RBF gradually absorb water from the atmosphere, lowering their boiling point. That’s why regular changes are essential—especially for track use.

MOTUL Brake Fluids Compared: RBF 600 vs RBF 660 vs RBF 700

Product	Dry Boiling Point	Wet Boiling Point	Ideal Use Case	Approx Cost (500ml)
RBF 600	312°C	204°C	Fast road & occasional track days	£9.99–£14.99
RBF 660	328°C	204°C	Regular track days & club-level racing	£17.99–£22.99
RBF 700	336°C	205°C	Pro racing & extreme heat conditions	£26.99–£31.49

Which Brake Fluid is Right for You?

Daily Driver / Fast Road Use:

Go for RBF 600. It’s a major upgrade over standard DOT 4 fluid and handles spirited driving well. If you only attend the occasional track day, this will still perform without issue.

Frequent Track Day Enthusiast:

Step up to RBF 660. With higher thermal resistance, it’s perfect for those who push their brakes hard on circuits or mountain passes. It gives a more consistent pedal feel and resists fade lap after lap.

Professional Motorsport or Heavy-Duty Racing:

RBF 700 is the top dog. It’s built for extreme heat, endurance racing, and carbon/ceramic systems. If you’re a serious competitor, this is the fluid you want.

Important Notes on Maintenance

• Flush your brake fluid regularly—at least once a year for road cars, more often for track use.

• Don’t mix RBF fluids with DOT 5 or silicone-based fluids.

• Keep fluids sealed and avoid contact with painted surfaces.

• Always bleed your brakes properly after replacing fluid.

Performance Starts With the Right Fluid

The best brake setup in the world won’t perform if your fluid can’t keep up. Whether you’re daily driving or door-to-door racing, matching the right brake fluid to your needs ensures consistent stopping power when it counts.

Explore the full MOTUL RBF range at Carbonwurks.com and choose the fluid that keeps your car braking like a pro.

If you’re not sure which fluid is best for your vehicle then just get in touch and we’d be happy to help and point you in the right direction!