Anybody using Castrol SRF racing brake fluid?

I recently read "Racing Under the Illusion of Grandeur" (an entertaining read), and in it, the author swears by Castrol SRF racing brake fluid.  He said it gives a firmer pedal, never boils, and (this part doesn't make sense to me) requires minimal bleeding.  It's expensive, at over $60 for a liter, but it if lasts longer, and performs better, than the usual stuff from Motul, Millers, Wilwood, etc., I might be interested, but the specs don't look any better than the less expensive stuff.  Any experience out there?  Thanks.

Castrol SRF and Prospeed RS683 are in a league of their own ... at least among brands you can easily find at the usual places. 

It is the best I've used and I've used all of the lesser fluids. Motul, Pagid, blah blah blah. They all boil. Granted, I drive a heavy ass car with hot and sticky pads on hot and sticky tires, but I berkeleyed around with all kinds of brake fluids last year on the Camaro to try to get it to last more than 14 minutes per session. Switching to SRF did it. I couldn't be happier with the stuff and I totally recommend it. It's worth the extra money for me simply because the extra $30 on a liter of fluid is cheaper than the money I am spending on track time I can't use because I have to come in after 14 minutes with no brakes.

This is running in the Camaro ('18 SS 1LE) on Pagid RSL2 pads now, Raybestos ST43s last year. In the 911, I ran Pagid RS14 Blacks and they'd cook cheaper fluid, too. 

If I can hustle my 3700lb beast around Blackhawk all day and even run some double sessions and the brake fluid isn't boiling, that's some good fluid.

Like I said, it's worth the money.

There are two things you care about - the propensity to boil when fresh, and the propensity to boil when "old."

The reason the second issue matters is that your brake components have little holes throughout the system that allow air to get in.  Air has moisture, and brake fluids by design attract water.  When water get into the fluids, it then gets dispersed throughout the system (again, by design).  This is usually not an issue for daily drivers as the fluid temperature does not go very high.  However, on track, when the fluids get above a certain temp, the water will boil way before brake fluid, so you have little bubbles that makes for a squishy pedal.  And nobody likes a squishy brake pedal on track...

So if you flush very frequently then you don't care that much about the second issue because the fluids won't have much time to attract water.  But if you track the car infrequently (like a few times a year vs. every weekend) and don't bleed before every event, then you should care.  

Castrol is great for both of the issues above, because its dry boiling point (when the fluid boils) is very high, and its wet boiling point (when there's water in the system) is also very high.  As someone who started with Prospeed, then moved to Castrol, and then went to Redline as I was tracking (and bleeding) more frequently, I have to say that Castrol is worth the price and I will stick with it going forward.  Also remember Castrol is like 60 bucks for a liter, where as most brake fluids are sold in 1/2 liters, so the price is closer to 2x, not 4x as some people think.  The downside is that once you open the package, you pretty much are committing to using the entire thing (remember the fluid attracts water, and once it's open the water from the atmosphere will start to seep through).  It's totally worth it if you're somewhat serious about tracking your car.  

Thanks for the responses - great info, bcp2011.  It really sounds like the SRF is worth the extra cost, especially if the alternative is bleeding very frequently, because you always lose some fluid during the bleeding process.  So, it seems like a no-brainer, as the cost should be a wash in the long run.  And good point about the other brands being sold in 1/2 liter bottles.  I will plan on using SRF next time around.

I do light track duty with my '16 WRX STI, a very heavy car to be sure in a very humid environment (my home tracks are PittRace and Mid-Ohio). I've only needed to do annual bleeds with Castrol SRF, and I daily drive my car year round. Many of my instructors and their students at the Porsche DEs do the same with their cars (E92 M3, Evo IX, Porsche 994, E30 M3, 911s, etc).

Needless to say I think it's great stuff and I don't currently have a brake cooling solution! Amazon sells it for a good price usually, and if you have a Prime rewards card you'll get 5% back.

I'm sure it's great stuff.  I haven't tried it.  I use a half-liter of Motul RBF 600 to flush my heavy-ass E92 M3 once a year at the start of track season, and proceed to HPDE and open-track my way through the spring, summer, and fall.  Sticky tires (100 TW) and brakes (PFC 01 or 08), DistMarVa humidity.  If it ever lets me down, now I know where to look for better,

In reply to Cloud9...68 : as someone who is forced to bleed brakes for every single event I agree it’s worth it. 

I race at Elkhart Lake which is 4 miles of brake killing track  I drove a solid ( non vented ) rotor very fast car and good brakes made a major difference.  

Think of it in horsepower terms!  Imagine how much horsepower you’d have to make to get your car to accelerate as fast as it stops!! 

In my case  we’re talking top fuel acceleration in reverse.  Only thing that stopped faster was the arresting wires on the flight deck of the carrier! 

A couple of points...

Yes, SRF is harder to boil, but...  Some of us have boiled it anyway.

SRF is not compatible with some other brake fluids.  You should evacuate the entire system and switch it all out.

JBasham said:

I'm sure it's great stuff.  I haven't tried it.  I use a half-liter of Motul RBF 600 to flush my heavy-ass E92 M3 once a year at the start of track season, and proceed to HPDE and open-track my way through the spring, summer, and fall.  Sticky tires (100 TW) and brakes (PFC 01 or 08), DistMarVa humidity.  If it ever lets me down, now I know where to look for better,

Keep in mind there is Motul RBF 660 as well. 

On four wheels I've only tracked Miata's that had Sport brakes or Wilwoods with 2 piece rotors, so fade and pad wear were never even a concern.

wvumtnbkr said:

A couple of points...

 

Yes, SRF is harder to boil, but...  Some of us have boiled it anyway.

 

SRF is not compatible with some other brake fluids.  You should evacuate the entire system and switch it all out.

Good point - what's the best way to completely evacuate a brake system?  Is it enough to thoroughly flush it with the SRF, or do you have to do some sort of vacuum evacuation procedure first?  And is it realistic to completely get the old stuff completely out of the ABS jungle?

In reply to Cloud9...68 :

The guys from Rooster Hall Racing (one of the bigger and more successful BMW CCA Club Race teams) told me to just do a “gravity flush and fill.” Basically, open the fluid reservoir cap and the bleeder nipples all around and let everything drip out. Keep an eye on the reservoir to keep it full of fresh fluid. Seems to work pretty well. 

I’ve had great results with some of the lesser Castrol stuff. I’ll keep the SRF in mind. 

Do we have a thread about bleeding brakes on modern cars? I hear rumors about the pedal never being the same...

Some cars require the ABS pump to be cycled when doing so, but that's all I can think of. The pedal in my 135i didn't feel any different when I had him flush the brakes and we didn't even do that (cycling the ABS pump).

In reply to LanEvo :

I use a Motive pressure bleeder to drain & refill ("bleed" really isn't the right term, because it's actually a process of replacing the old fluid with fresh stuff, but of course it bleeds the system at the same time) my system about twice a year.  I'm not seeing how Rooster Hill Racing's method would do a better job of replacing the old fluid with fresh, but maybe I'm missing something.

In reply to Cloud9...68 :

The problem I was having was that after I used a power bleeder (mine was also a Motive, BTW) there was still some mushiness in the pedal. I seemed to have some air trapped in the rear lines that wouldn't come out even after multiple flushes.

I was pitted next to the guys from Rooster Hall and they offered to help. The point of the gravity flush was that somehow (don't ask me how!) you'd get more of the old fluid out and bleed out more of the trapped air. Not sure if this had to do with the ABS system or something else. I think they said it was also supposed to be gentler on the master cylinder. I don't really know the theory, but it worked like a charm.

In reply to LanEvo :

How long does this take without external pressure and just atmospheric pressure?

I've tried gravity bleeding a few time before. To be honest, I think it sucks. It takes FOREVER to go from old fluid to a system full of new fluid. Using the normal two person method is at least ten times faster. I plan on getting a pressure bleeder one of these days though.

Yeah, I've tried multiple methods - Motive only, two-person only, Motive PLUS two-person simultaneously, Motive with tapping on the calipers to break up air bubbles, and no matter what, I always have a bit of mushiness to my pedal, which I've just resigned myself to living with, as it doesn't seem to do any harm.  I never get any air bubbles when I replace my fluid, but I still always have a somewhat mushy pedal.  There are a lot of people who swear by this method or that one, and an equal number of detractors of each method.  This has always been a frustrating topic for me, so to be honest, I'm hoping (but truthfully not really expecting) the Castrol SRF to be the "magic fairy dust" answer to my braking needs.  I'm currently using Motul RBF660, by the way.

Pressure, gravity, etc, I've never been successful with. The two person bleed has by far always given the best results on the cars I've done it with.

bcp2011 said:

In reply to LanEvo :

How long does this take without external pressure and just atmospheric pressure?

Pretty much forever. 

z31maniac said:

Pressure, gravity, etc, I've never been successful with. The two person bleed has by far always given the best results on the cars I've done it with.

When we did the gravity bleed, we followed with regular 2-person bleed. 

LanEvo said:

z31maniac said:

Pressure, gravity, etc, I've never been successful with. The two person bleed has by far always given the best results on the cars I've done it with.

When we did the gravity bleed, we followed with regular 2-person bleed. 

So like you used half a liter for gravity and half with two people?

I use my Motive and tap on the calipers with a rubber mallet.  This has always for well for me *unless* I've let the Motive run dry and sucked air up into the lines.  Then it's nearly impossible to get the air out of the system again without cycling the ABS pump. 

So I always, always keep a very close eye at the level of fluid in the Motive....