Brake fluid isn't always the first thing people think about when upgrading a performance car, but as speeds increase and braking gets more demanding, having the right fluid becomes increasingly important.
In our latest video, Percy and I take a look at the Motul brake fluid lineup, including DOT 5.1, RBF 600, RBF 660, and RBF 700, to explain the differences and help determine which fluid makes sense for your car.
WHY IT MATTERS:
Your braking system relies on hydraulic pressure to transfer the force you apply at the brake pedal to the brake calipers. The problem is that braking generates heat—and repeated hard braking can generate a lot of it.
If brake fluid reaches its boiling point, vapor can begin forming within the hydraulic system. Because vapor is compressible, this can result in a soft pedal and reduced braking consistency.
That's why boiling point is one of the most important specifications when choosing a performance brake fluid.
You'll typically see two numbers listed: dry boiling point and wet boiling point.
Dry boiling point represents fresh brake fluid, while wet boiling point represents fluid that has absorbed a specified amount of moisture. DOT 3, DOT 4, and DOT 5.1 fluids are hygroscopic, meaning they absorb moisture over time. This is one of the reasons regular brake fluid changes are important, especially on cars that see track use.
Motul DOT 5.1 – Street & Performance Use
Motul DOT 5.1 is a 100% synthetic, glycol-based brake fluid intended for hydraulic brake and clutch systems requiring DOT 3, DOT 4, or DOT 5.1 fluid.
According to Motul's technical information—and the product we're using in our video—DOT 5.1 has a:
Dry boiling point: 522°F (272°C)
Wet boiling point: 365°F (185°C)
DOT 5.1 is particularly well suited to modern street cars, including vehicles equipped with ABS and other electronically controlled braking systems.
For a daily-driven performance car that sees spirited driving but isn't regularly exposed to sustained track temperatures, DOT 5.1 is a great option.
Motul RBF 600 – Stepping Into Track Use
Next is Motul RBF 600 Factory Line, where we move into Motul's DOT 4 racing brake fluids.
RBF 600 has a:
Dry boiling point: 594°F (312°C)
Wet boiling point: 401°F (205°C)
That represents a significant increase in temperature capability compared with DOT 5.1.
RBF 600 is a popular choice for performance cars that see track days, HPDE events, autocross or other situations involving repeated hard braking. For many enthusiasts, it offers a great balance between street usability and the thermal performance needed at the track.
Motul RBF 660 – More Temperature Headroom
For more demanding track and competition applications, Motul offers RBF 660 Factory Line.
RBF 660 increases the dry boiling point to:
Dry boiling point: 617°F (325°C)
Wet boiling point: 401°F (205°C)
The interesting part here is that the listed wet boiling point remains the same as RBF 600. The major difference is the additional dry boiling-point capability.
That extra temperature headroom makes RBF 660 a good option for dedicated track cars, race cars and vehicles with braking systems that regularly experience extreme temperatures.
Motul RBF 700 – Maximum Temperature Performance
At the top of Motul's RBF lineup is RBF 700 Factory Line.
RBF 700 is designed for extremely demanding racing applications and offers the highest dry boiling point of the fluids we're comparing:
Dry boiling point: 637°F (336°C)
Wet boiling point: 401°F (205°C)
Again, the wet boiling point remains at 401°F, but the dry boiling point continues to increase.
For most street cars, RBF 700 is far beyond what's necessary. It's intended for serious competition environments where brake temperatures can become extreme and every bit of additional thermal capability matters.
Comparing the Motul Brake Fluid Lineup
Here's how the four fluids compare:
| Brake Fluid | Dry Boiling Point | Wet Boiling Point | Recommended Use |
|---|---|---|---|
| Motul DOT 5.1 | 522°F | 365°F | Street / Performance |
| Motul RBF 600 | 594°F | 401°F | Track Days / HPDE |
| Motul RBF 660 | 617°F | 401°F | Racing / Heavy Track Use |
| Motul RBF 700 | 637°F | 401°F | Extreme Competition |
One important takeaway is that DOT 5.1 isn't automatically a higher-performance fluid than DOT 4 simply because of the number in its classification. DOT ratings cover several characteristics of a brake fluid, not just its maximum boiling point.
Motul's RBF 600, 660, and 700 are all DOT 4 fluids, yet they offer significantly higher dry boiling points than Motul DOT 5.1 because they're specifically formulated around the demands of racing.
Which Brake Fluid Do You Need?
Like most performance upgrades, choosing brake fluid should be based on how you actually use the car.
For a daily-driven performance car, Motul DOT 5.1 offers plenty of capability. If you're regularly taking the car to track days, RBF 600 provides a substantial increase in temperature resistance.
As braking demands increase, RBF 660 provides additional dry boiling-point capability for more serious track and race applications, while RBF 700 sits at the top of the range for competition vehicles operating under extreme conditions.
More importantly, even the best brake fluid needs to be maintained properly. Brake fluid absorbs moisture over time, which is why regular flushing and bleeding should be part of any performance or track car's maintenance routine.
Check out our full video as Percy and I break down the Motul brake fluid lineup, explain the differences between each option, and discuss which one makes the most sense for your application.