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      03-18-2017, 08:30 AM   #1
tadmcmichael
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Castrol SRF Service Life

I hear that the SRF and other high performance brake fluids don't have a long service life. Sounds like a year tops versus say two years with OEM fluid.

What is the explanation of this? Are these racing fluids simply more hygroscopic? Is Castrol SRF any harder on brake lines, piston seals, etc.? Will I notice a softer pedal with SRF because of increased compressibility?

I have first track days of the season in a couple weeks. I do about 3 or 4 a year and don't want to flush (or even bleed) more than once a year. Stock brakes with PFC 08s and Ti shields. Ran ATE last year without issue, but stock tires kept me from pushing very long. Better tires this season makes me believe the ATE will boil.
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      03-18-2017, 08:58 AM   #2
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I put fresh SRF in once a year...don't do anything else.


7 to 9 track weekends per year.
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      03-18-2017, 09:10 AM   #3
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I change SRF once a year and track the car ~30 days

I love that stuff

By the way, you may want to get the PFC DD front rotors for the E92. They make a large difference
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      03-18-2017, 10:06 AM   #4
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Quote:
Originally Posted by SYT_Shadow
I change SRF once a year and track the car ~30 days

I love that stuff

By the way, you may want to get the PFC DD front rotors for the E92. They make a large difference
I keep waiting for the V3 DD rings to come out for our car. Was supposed to be introduced a couple years ago.

Will stay on stock rotors until I tear them up. Then will likely get the Stoptech Aerorotors unless the V3 DDs have been introduced.
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      03-18-2017, 02:22 PM   #5
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Quote:
Originally Posted by tadmcmichael View Post
I hear that the SRF and other high performance brake fluids don't have a long service life. Sounds like a year tops versus say two years with OEM fluid.

What is the explanation of this? Are these racing fluids simply more hygroscopic? Is Castrol SRF any harder on brake lines, piston seals, etc.? Will I notice a softer pedal with SRF because of increased compressibility?

I have first track days of the season in a couple weeks. I do about 3 or 4 a year and don't want to flush (or even bleed) more than once a year. Stock brakes with PFC 08s and Ti shields. Ran ATE last year without issue, but stock tires kept me from pushing very long. Better tires this season makes me believe the ATE will boil.
I believe that the explanation for this is that performance brake fluids with higher dry boiling temps tend to be more hygroscopic than your run-of-the-mill DOT4 brake fluid which will cause degradation in performance sooner and tend to increase moisture in the brake lines.

SRF however has a much higher wet boiling point than most other brake fluids which presumably means that you can keep it in the system for longer than your average performance DOT4. That being said I've kept Motul RBF600 in for about a year (got lazy) and haven't really noticed anything bad one way or the other.

Regarding PFC DD V3 rotors:
http://www.hpashop.com/Performance-F...C-DD-1M-M3.htm
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      03-18-2017, 11:49 PM   #6
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Ultimately, it all comes down to how hard you are on the brakes. If you don't push the car hard enough, boiling brake fluid will not be a concern for you and it will last a long time. You can boil any fluid. But with SRF's wet boiling point being so high, even when the fluid is compromised, it still works fairly well. I've been to basically every track in California, and most would say I push the car pretty hard. The only track that flat out boiled my SRF and then led to a crappy pedal feel the next event was Thermal Club. That track is VICIOUS on brakes. My friend owned a BBK for a year with no issues. Thermal turned his calipers from orange to bronze in one day. And to the fluid's credit, I didn't know at Thermal that the fluid was boiled. It was on my next trip to Buttonwillow that I grabbed the brakes and was like Whoaaaa!!!!!! Haha! I was still able to manage the brakes thst day even though the fluid was hosed.

Honestly, if you track a car, most fluids should probably be tended to at least once a year.
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      03-19-2017, 08:31 AM   #7
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Quote:
Originally Posted by ayao View Post
Thanks! I did't know these had been introduced yet.

Think I will go with the SRF. Don't really see any downsides to it.
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      03-19-2017, 11:33 AM   #8
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It depends.

If you pay someone to bleed brakes then SRF makes total sense. If you DIY it, I would just use Motul 600 or something similar.

IIRC, the dry and wet boiling points are about the same for all of the high performance fluid. The only difference is SRF doesn't continue to feel mushy once you boil it.

But when you boil brake fluid, you should be inspecting your dust boots and seals. Those components were quite hot and probably close to or at their melting point as well. I've seen people think since they've got SRF in, they're fine. Also keep in mind you've got condensation building up in your brake system which leads internal corrosion of your non-aluminum brake components.

You've also lowered the boiling point of your brake fluid significantly so you're far more likely to boil it again.

Even on my E90 M3, I've run Motul RBF600 and Stoptech STR600...never had an issue.
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      03-19-2017, 11:35 AM   #9
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Quote:
Originally Posted by tadmcmichael View Post
I keep waiting for the V3 DD rings to come out for our car. Was supposed to be introduced a couple years ago.

Will stay on stock rotors until I tear them up. Then will likely get the Stoptech Aerorotors unless the V3 DDs have been introduced.
Like someone pointed out later, the v3s were introduced with them. Two guys I track with use them with great results, which is unsurprising given the excellent performance I saw in my E46 with the pfc dd rotors.

On the E92 and E90 we run the PFC BBK. I just replaced one of the rotors and the v3 mounting system is so impressive... brain explodes lol

Yesterday I bled the SRF after one year. It was slightly yellow. It's impressive stuff.
One day they'll build SRF v2.0 and price it at $100/bottle and I'll be the first in line!
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      03-20-2017, 12:15 AM   #10
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Quote:
Originally Posted by bigjae1976 View Post
IIRC, the dry and wet boiling points are about the same for all of the high performance fluid. The only difference is SRF doesn't continue to feel mushy once you boil it.
According to this chart comparing 79 brake fluids, SRF's Wet Boiling point is 100ºF+ higher than most of the fluids on the chart. Torque T700 is the closest and it's still 79ºF away..... I would say that's a statistically significant difference, no?

https://www.lelandwest.com/brake-flu...ison-chart.cfm
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      03-20-2017, 12:31 AM   #11
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Quote:
Originally Posted by dogbone View Post
Quote:
Originally Posted by bigjae1976 View Post
IIRC, the dry and wet boiling points are about the same for all of the high performance fluid. The only difference is SRF doesn't continue to feel mushy once you boil it.
According to this chart comparing 79 brake fluids, SRF's Wet Boiling point is 100ºF+ higher than most of the fluids on the chart. Torque T700 is the closest and it's still 79ºF away..... I would say that's a statistically significant difference, no?

https://www.lelandwest.com/brake-flu...ison-chart.cfm
I didn't "IIRC"...that would make a bit of a difference

I did verify that you can get SRF on Amazon for $65 which is what I remember being the lowest price.

I use Stoptech STR-600 which i think is rebranded Motul except $3/bottle cheaper.
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      03-20-2017, 09:28 AM   #12
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Quote:
Originally Posted by tadmcmichael View Post
I hear that the SRF and other high performance brake fluids don't have a long service life. Sounds like a year tops versus say two years with OEM fluid.

What is the explanation of this? Are these racing fluids simply more hygroscopic? Is Castrol SRF any harder on brake lines, piston seals, etc.? Will I notice a softer pedal with SRF because of increased compressibility?

I have first track days of the season in a couple weeks. I do about 3 or 4 a year and don't want to flush (or even bleed) more than once a year. Stock brakes with PFC 08s and Ti shields. Ran ATE last year without issue, but stock tires kept me from pushing very long. Better tires this season makes me believe the ATE will boil.

The whole point of using SRF, with its amazingly high wet boiling point, is that you don't have to replace it after every event. Many of us who run SRF flush it once per year: right at the beginning of track season.

Some prefer using other fluids like the Motul RBF (which have lower wet boiling points) because it's cheap and they want to flush it after every event. I think that is still a bit too often, but I guess it sorta comes down to personal preference. A happy medium might be flushing every 3 or 4 events.
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      06-21-2018, 06:35 PM   #13
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Somehow boiled my SRF fluid after 5 track events and being in the car since September 17' Super inconsistent pedal feel at Laguna last weekend. Not fun coming to turn 2 downhill at 125mph.
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      06-21-2018, 06:38 PM   #14
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PCA doesn't care what high-performance brake fluid you run, they mandate change every 6 months, documented by a shop. OEM fluid every 3 months.
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      06-21-2018, 08:22 PM   #15
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Quote:
Originally Posted by VictorH View Post
PCA doesn't care what high-performance brake fluid you run, they mandate change every 6 months, documented by a shop. OEM fluid every 3 months.
I have never lied or misled on a tech form.
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      06-22-2018, 11:08 PM   #16
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Originally Posted by CorruptCommie View Post
I have never lied or misled on a tech form.
“__ Windshield free of cracks”

*check*
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      06-23-2018, 06:32 AM   #17
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Quote:
Originally Posted by MPower7 View Post
Somehow boiled my SRF fluid after 5 track events and being in the car since September 17' Super inconsistent pedal feel at Laguna last weekend. Not fun coming to turn 2 downhill at 125mph.
What brakes?
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      06-23-2018, 07:57 AM   #18
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Sadly torque RT700 is hard to get it might even be completely off the market.

SRF is good enough and probably the best option if you don't bleed frequently.

I bleed at the calipers after or before every event so SRF's advantages don't mean much to me particularly at its price point.

Motul 600 should be good enough more most users and its at a good price point.

I use PFC 665 that I order by the case.

The top line AP radi-cal fluid is also supposed to be excellent but there are a very limited number of suppliers.
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      06-23-2018, 01:43 PM   #19
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Quote:
Originally Posted by MasterP View Post
Sadly torque RT700 is hard to get it might even be completely off the market.

Torque touts their ultra-low compressibility but I never noticed any difference with it over the other high-temp fluids. If you can't find it, try searching for Prospeed RS683 Xtreme -- it's the same product with a different label, and way easier to find. My local Porsche dealer even carries it.
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      06-25-2018, 09:55 AM   #20
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Quote:
Originally Posted by roastbeef View Post
What brakes?
Stock Brakes, PFC 08 pads and Nitto NT-01's. I flushed it this weekend and it was really dark!
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      06-25-2018, 10:21 AM   #21
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Quote:
Originally Posted by MPower7 View Post
Quote:
Originally Posted by roastbeef View Post
What brakes?
Stock Brakes, PFC 08 pads and Nitto NT-01's. I flushed it this weekend and it was really dark!
Oooffff! Yea, oem rotors can't handle laguna!
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      06-25-2018, 11:30 PM   #22
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Quote:
Originally Posted by roastbeef View Post
Oooffff! Yea, oem rotors can't handle laguna!
I ran 3 days there in August 2016 (when I still had a modicum of skillz) on stock rotors and NT-01's. No muss. No fuss. Think I ground off about 3 thousandths of an inch of rotor. New PF-08's.

Laguna is hard on brakes though. No question. Just don't stand the car on it's nose every braking zone and they'll be fine. Not optimal, but fine.
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