We don’t want mushy brakes on the track, right? The following article explains our take on various brake fluids review separated into three tiers based on price point. Brake fluids have a maximum operating temperature; if this number is exceeded, your fluid will boil and braking pressure will cease to exist. Tip: If this ever happens, pump the brake pedal to generate some pressure and try to go straight even if it means going off course (if possible).
Brake fluid deterioration:
If moisture and/or water is introduced into the brake fluid, you can expect the maximum temperature the brake fluid can withstand to drop since water boils at a lower temperature than the brake fluid itself. So it is important to maintain your brake fluid at optimal life.
No brake line is perfect nor packaging so the life of brake fluid is always dwindling with moisture seeping in from various places. Once it boils, your brake fluid no longer has the properties that exerts enough pressure on the pistons. You will only want to use a DOT 4 rated fluid or DOT 5.1 which has the correct characteristics for a performance car. Use this brake fluid review guide to see what brake fluid would work best for you.
*DOT stands for department of transportation and often provides specifications and safety regulations for car part manufacturers to adhere by.
If you haven’t already please read our brake fluid comparison guide. Below we offer our own recommendations and experiences with the many brake fluids on the market.
Wet Boiling Point – Temperature that brake fluid boils with moisture.
- The wet boiling point is more important than the dry boiling point as the latter is often tested in a lab under fresh brake fluid and ideal conditions. You want to look at how it performs with moisture, since without a doubt moisture is going to be introduced into your brake fluid over time. You can think of this measure as an average performance rating of your brake fluid.
Hygroscopicity – How likely/fast brake fluid will absorb water.
- This determines how often you will need to do a brake flush, or a complete change out of your brake fluid.
Dry Boiling Point – Temperature that brake fluid boils without moisture.
- Occasionally, some fluids are known to hold their dry boiling point longer than usual. This is usually due to lower hygroscopicity rating of their fluid.
Compressibility – How compressible the brake fluid is (Pedal feel).
- Fluids often compress more under higher temperatures. This means that while the brake fluid will perform its job, it can leave the pedal feeling rather spongy. You want a low compressibility at any temperature.
PH – How acidic the brake fluid is.
- You want something as close to neutral as possible, since you don’t want your brake system components to wear due to corrosion. Certain chemicals may increase the wet or dry boiling point however, at the expense of a higher PH which can prematurely wear out your brake system.
We designate 3 tiers of brake fluid from top performing to lowest performing. Here are some of the popular brake fluid brands used in amateur racing.
Tier 1 Brake Fluids ($70+ for 1L):
- Castrol SRF
- Endless RF-650
- Project Mu 335
- Torque RT700
- Brembo HTC 64T
(Higher Rating is Better)
Castrol SRF Review:
While Castrol SRF brake fluid performed well during track days, our pedals did feel spongy afterwards due to the compressibility of the fluid at higher temperatures. The brake pedal usually returns back to normal after a few hours and some cool down. We commonly see Castrol used for rally racing and racing series.
With Endless we immediately noticed the stiff pedal which we like. Porsche owners have noted that Endless is the OE fluid for factory Porsche 911 GT3 Cup car. Endless fluid did not leave my brake pedal feeling spongy at all after a track day.
Torque RT700 is hard to find, but on paper, it is the best overall performing brake fluid with similar pedal feeling to Endless at a lower cost.
Project Mu 335:
We have boiled Project Mu 335 brake fluid before on a track day which resulted in a spongy pedal that did not firm back up even after cooldown period. Which is weird because by looking at the numbers it should outperform the Endless fluid. We found that one nice thing about Project Mu is that the fluid changes colors when it is boiled, making bleeding calipers easier.
Brembo does not post specs, so we are a bit wary of using them as our choice of brake fluids but we are testing them out anyways. We believe that Brembo is a trusted company and have no reason to doubt their brake fluid isn’t capable for racing. Fun fact: Brembo and Endless are the only two brake fluids used in F1.
Recommendation: Endless RF-650 (Compressibility) or Castrol SRF (Wet Boiling) or Torque RT700 (Overall – Hard to find)
Tier 2 Budget Brake Fluids ($20+ for 1L):
- Motul RB 600
- Motul RB 660
- Stoptech STR-660
- Stoptech STR-600
- ATE Super Blue/Type 200
- Brembo LCF 600
(Higher Rating is Better)
Some at BuildJournal dislike Tier 2 fluids because we can potentially boil them at the track days. Some people had good results but most of the times the brake fluid boils. They are solid upgrades over the stock brake fluid, so you could give these fluids a try if you are still on OEM fluid and looking for a small upgrade.
A couple years back when we were getting into the tracking, we remember there was one brand everyone was talking about getting: Motul. Specifically the Motul RBF 600. It is widely popular due to the larger distribution network. We picked ours up at the local Nissan dealership for crying out loud. We’ve had great experiences with the Motul RBF 600 and although we probably didn’t run them near the boiling points, later on as we got more seat time in our cars we started boiling them. For me I remember going into Turn 11 at Auto Club Speedway Roval when all of a sudden my brakes felt mushy. Not a good feeling. And doesn’t make me comfortable to really push the car and late brake.
Stoptech STR660 is a very nice brake fluid for daily driving and occasional canyon run. Oscar runs this fluid in his father’s Imola M3 and it performs very well in terms of price to performance and hygroscopicity. It has been a couple years since the last brake bleed and it still feels about 80-90% of the original performance. However, his father does not track his car.
ATE Super Blue was the first brake fluid that most try out due to its unique blue dye and good feedback. It is a very good fluid however, we do not recommend it for the following reasons. It is no longer legally sold in the US due to its dye and it will stain your reservoir blue making it really hard to see the max and min marks. During track days we were able to boil it and as a result ran off the track. Usually after the track day, we find ourselves bleeding the calipers due to the mushy feel. Type 200 is the alternative Super Blue without the dye. Originally people switched between Super Blue and Type 200 so that they could see when new brake fluid was bled out.
Brembo LCF 600:
Andrew is testing this out at the moment.
OEM felt great however after some time, the pedal would feel mushy. At the price point that BMW sells their brake fluid at…we would rather get Motul or StopTech
Recommendation: StopTech STR-660 ($ to Performance) or Brembo LCF 600 (Overall) or Motul RB 600 (Higher Wet Boiling)
Tier 3 Budget Brake Fluids ($5+ for 1L):
- Generic DOT 4
In case of emergency, you can use off the shelf brake fluid. However, you will ruin your brake fluid performance by shifting the numbers to the lowest denominator ($5 brake fluid). Check the mixture recommendation on our brake fluid comparison guide to ensure compatibility. I flushed my friend’s car with the autozone special and it felts alright as fresh fluid will always feel better than old OEM fluid. After a few short months, the mushy feeling came back. Stick with Tier 2 and above brake fluids.
Recommendation: Do not buy.
Questions or suggestions? Comment below! Special Thanks to The Following People: Lorrie Ma (bCaHnIaCnKa @ M3Forum), Melony Gani, Allan Shen (xdaznboi)