Brake fluid is one of those things that rarely gets talked about until it becomes a problem.
RBF660 or RBF700? The quick answer
RBF660 is our usual choice for compatible road and track-day cars. RBF700 gives fresh fluid an extra 11°C of dry-boiling margin for more demanding circuit use. Both are DOT 4; the correct choice still depends on your braking system’s fluid and viscosity requirements.
See current prices, availability and estimated delivery on each product page. Check how many bottles to order.
People will spend hundreds on pads, discs, braided lines and tyres, then head out on track with old fluid that's been in the car for years. The result? A long pedal halfway through a session and a very nervous drive back to the pits.
I've run Motul RBF660 in my own BMW M2 Competition for years and it's never let me down. The car sees fast road driving and regular track use, and even with the weight and performance of the M2 Comp, I've never managed to get the fluid to complain.
That said, there are situations where Motul RBF700 makes more sense.
So if you're trying to decide between the two, here's what you actually need to know.
Motul RBF660 vs RBF700: specifications compared
| Specification | RBF660 | RBF700 |
|---|---|---|
| Fluid standard | DOT 4 | DOT 4 |
| Dry boiling point | 325°C | 336°C |
| Wet boiling point | 205°C | 205°C |
| Viscosity at −40°C | 1,698 mm²/s | 1,580 mm²/s |
| Bottle size | 500ml | 500ml |
The useful difference: RBF700 has a higher dry boiling point, while both current data sheets list the same wet boiling point. “Wet” describes moisture absorbed into the fluid, not simply driving in rain. RBF700 does not remove the need for fresh fluid and correct maintenance.
Sources: Motul RBF660 technical data sheet and Motul RBF700 technical data sheet, both dated September 2025 and linked from Motul’s UK product pages. Older RBF660 literature quotes different figures; check the label and applicable data sheet for the fluid supplied.
Looking purely at the numbers, RBF700 has the advantage thanks to its higher dry boiling point.
The question is whether your car actually needs it.
For most people, the answer is probably no.
Why Brake Fluid Matters
When you're driving hard, brake temperatures rise incredibly quickly.
Every time you hit the brakes, heat transfers from the pads and discs into the calipers and ultimately into the brake fluid. If the fluid gets too hot and starts to boil, vapour forms inside the system.
Unlike fluid, vapour compresses.
That's what causes the dreaded soft pedal that nobody wants to experience at the end of a long straight.
The harder you drive, the more important your brake fluid becomes.
Motul RBF660: The Sweet Spot for Most Cars
If someone asks me what brake fluid they should run in a fast road or track day car, my answer is usually RBF660.
Brake-fluid delivery: availability varies by destination. The linked Motul fluid listings are UK buying routes; customers ordering outside the UK should confirm brake-fluid supply and shipping with us before ordering.
It's the fluid I run in my own BMW M2 Competition and it's proven itself time and time again.
The M2 Comp isn't exactly a lightweight car. Mine runs upgraded pads and sees plenty of hard use, yet RBF660 has always delivered a consistent pedal and reliable braking performance.
That's why it's become one of the most popular performance brake fluids on the market.
Choose Motul RBF660 if:
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Your car is mainly driven on the road.
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You do occasional or regular track days.
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You have upgraded pads and discs.
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You want excellent pedal feel and temperature resistance.
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You want proven performance without spending more than necessary.
RBF660 is worth considering for performance cars such as the BMW M2, M3, M4, Golf R, Civic Type R and GR Yaris, where the exact model and fitted brake system’s requirements allow it. A model name alone does not confirm fluid compatibility.
In reality, it's more brake fluid than most drivers will ever need.
Motul RBF700: When You're Really Leaning on the Brakes
RBF700 is aimed at drivers who are genuinely pushing their braking systems to the limit.
We're talking about cars running slicks or semi-slicks, aggressive race pads, big brake kits and spending a lot of time on circuit.
The higher dry boiling point gives you extra temperature headroom when everything is getting seriously hot.
Choose Motul RBF700 if:
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You do frequent track days.
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You compete in motorsport.
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You're running slick or semi-slick tyres.
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You use aggressive race pads.
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Your car generates huge brake temperatures.
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You've experienced fluid-related fade with RBF660.
For dedicated track cars and race cars, that extra margin can be worthwhile.
Is RBF700 Better?
On paper, yes.
In the real world, not necessarily.
This is where a lot of comparison articles get it wrong.
Just because one product has a higher specification doesn't automatically make it the right choice.
If you're driving a fast road car that sees a handful of track days each year, there's a very good chance you'll never get close to the limits of RBF660.
I've certainly never found the limit in my M2 Competition.
Unless you're consistently generating extreme brake temperatures, the difference between the two fluids may be impossible to notice from behind the wheel.
What I Run in My BMW M2 Competition
I get asked this quite a lot.
My own BMW M2 Competition runs Motul RBF660.
The car sees spirited road driving and regular track use, and I've never felt the need to move to RBF700.
Pedal feel remains consistent, braking performance stays strong throughout sessions and it's proven itself to be completely reliable.
Could I run RBF700?
Absolutely.
Do I need to?
No.
That's why I generally recommend RBF660 to most M car owners unless they're doing serious circuit work.
Can You Use RBF660 and RBF700 on the Road?
Yes.
Both are high-performance DOT 4 brake fluids and can be used in compatible road car braking systems.
The important thing is maintenance.
Brake fluid naturally absorbs moisture over time, which lowers its boiling point. That's why regular fluid changes are important regardless of which fluid you choose.
How Often Should You Change It?
Follow the vehicle and brake-system manufacturer’s service interval, adjusted for your use. Frequent or demanding track use can require more frequent changes and checks; ask your workshop to set a suitable schedule.
Fresh fluid is cheap insurance compared to the cost of a ruined track day.
Choose your fluid and order the right quantity
RBF660: road and track-day value
Choose RBF660 when your braking system is compatible and you want high-temperature performance for road driving and track days without paying for RBF700’s extra dry-boiling margin.
View RBF660 500ml — price & availability
RBF700: extra margin for demanding track use
Choose RBF700 when your compatible braking setup and circuit use justify the higher dry boiling point. A soft pedal still needs diagnosis; changing fluid grade alone does not resolve every braking fault.
View RBF700 500ml — price & availability
How many 500ml bottles do you need?
Use the quantity selector on the single-bottle product page: 1 bottle = 500ml; 2 bottles = 1 litre; 3 bottles = 1.5 litres. These are bottle quantities, not a guarantee of the amount needed for your car. Confirm the full bleed or flush requirement with the vehicle or brake-system manufacturer or your workshop before ordering.
Check compatibility first: confirm the specified fluid standard and any low-temperature or low-viscosity requirement. DOT 4 on its own is not universal vehicle approval. Do not substitute either fluid where a different specification is required, and do not mix with silicone DOT 5 or mineral-based LHM fluid.
Delivery: check the current estimate on the selected product page and the delivery charge at checkout for your basket and destination. These are UK buying routes; for delivery outside the UK, confirm brake-fluid supply and shipping with us before ordering.
Unsure about suitability or volume? Ask us about your brake-fluid choice with your model, year and brake setup.
Which One Should You Buy?
Once compatibility and the required quantity are confirmed, choose according to your use:
Buy Motul RBF660 if:
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Your car is used on the road.
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You do occasional or regular track days.
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You want the best balance of performance and value.
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You drive a performance road car like an M2, M3, Golf R or Civic Type R.
Buy Motul RBF700 if:
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Your car spends most of its life on track.
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You race competitively.
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You're running slick tyres and aggressive race pads.
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You regularly generate extreme brake temperatures.
Final Verdict: Motul RBF660 vs RBF700
Both are excellent brake fluids.
The difference is that RBF660 suits the vast majority of enthusiasts, while RBF700 is aimed at drivers operating at the sharper end of track driving and motorsport.
Personally, I run RBF660 in my BMW M2 Competition and have never felt the need for anything more. It offers fantastic pedal feel, excellent temperature resistance and has proven itself on both road and track.
If you're building a dedicated track or race car, RBF700 gives you additional temperature headroom.
For everyone else, RBF660 remains one of the best performance brake fluids you can buy.
FAQs
Is Motul RBF660 good for track days?
Absolutely. It's one of the most popular track day brake fluids available and it's what I run in my own BMW M2 Competition.
Is Motul RBF700 better than RBF660?
It has a higher dry boiling point, but that doesn't automatically make it the better choice. Most fast road and track day cars will be perfectly served by RBF660.
Can I mix Motul RBF660 and RBF700?
Follow Motul’s guidance to avoid mixing and use the correct full flush procedure when changing fluid. Do not mix either fluid with silicone DOT 5 or mineral-based LHM. Have a competent workshop confirm the correct procedure for your braking system.
Is Motul RBF660 DOT 4?
Yes. Motul RBF660 is a high-performance DOT 4 racing brake fluid.
Is Motul RBF700 DOT 4?
Yes. Motul RBF700 is also a high-performance DOT 4 racing brake fluid.
Which Motul brake fluid should I use for my BMW M car?
For most BMW M cars, including the M2 Competition, M3 and M4, I'd recommend Motul RBF660. If the car is heavily track-focused or used for competition, then RBF700 may be worth considering.
Planning the rest of your brake setup?
Keep fluid choice separate from pad and disc fitment. Standard F8X iron brakes and the F87 2NH system use different components. Our Pagid buying guide and Endless buying guide explain the front and rear routes. Confirm the fitted hardware before selecting parts.
