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Discussion summary
YOUR RESEARCHAmerica's answer to SRF!
Leading reported evidence
Use borate ester (2% +/-1% air) as a base material
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Suggestion · Original poster
Castrol SRF use Silicate Ester as a base material whereas Prospeed RS683 and all DOT 4 compliant brake fluids use borate ester (2% +/-1% air) as a base material.
Leading evidence: 'Use borate ester (2% +/-1% air) as a base material' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Use borate ester (2% +/-1% air) as a base material' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
After using SRF for several years, I just switched to Prospeed at my race shop's advice.
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Use borate ester (2% +/-1% air) as a base material
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion · Original poster
Castrol SRF use Silicate Ester as a base material whereas Prospeed RS683 and all DOT 4 compliant brake fluids use borate ester (2% +/-1% air) as a base material.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
10 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T044418Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Professional race teams are switching over to Prospeed RS683 Extreme Performance Brake Fluid. As a technical supplier to Andretti Autosport, the Prospeed RS683 brake fluid has outperformed the competition in the labs and on the track. Don't believe it? check out these two links. Chuck
Characteristics of brake fluid:
http://www.imgt3performance.com/prospeedrs683.aspx
Why RS683:
http://www.imgt3performance.com/prod...3-brake-fluid/
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Buy three -- get one free! And free shipping!* (Enter quantity (4) plus promo code RS1 at checkout).
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At $40 for a .5L it is more expensive than SRF at $75 a liter. Nice that it is USA based since Castrol is UK based but in all my years I have never had my SRF let me down in racing or DE. You'd think the US based product would be cheaper since there is no import tax.
After using SRF for several years, I just switched to Prospeed at my race shop's advice. I've never been happy with the soft pedal feel from SRF, & 683 is supposed to be less compressible. I'll be racing on it in two weeks & we'll see how it does.
I remember meeting the guys behind Prospeed RS683 at last years Club Race at HighPlains. Good to see an American brand getting wider distribution and offering more variety beyond SRF and Motul. I'll give it a try on my next brake fluid change.
It certainly is the air, but not exactly for the reason you think... silicate ester is the base used in Silicone based brake fluids, 13% (+/- stdev of 6%) of this material is air. as the fluid sustain damaging heat and pressure the base material experiences compression that leads to changes in pedal pressure after 15 to 20 minutes of peak breaking. Castrol SRF use Silicate Ester as a base material whereas Prospeed RS683 and all DOT 4 compliant brake fluids use borate ester (2% +/-1% air) as a base material. Silicate ester is a material that is related to silicone. Please note it is NOT silicon but is related. This fact allows the silicate ester based brake fluid to have a much higher wet ERBP. However, the downside to silicate ester as a base material in brake fluid is increased compressibility and a shorter shelf life.
Professional race teams who prep cars for a living who have experienced fade with silicate ester based fluids when sustaining high temperature and pressure for extended periods. The high temp formulation along with the stability of RS683 under the same conditions is where Prospeed begins to shine...it builds confidence as your pressing hard when others are less efficient...That's why race teams are starting to become believers.
I have never noticed what I would consider a soft pedal in your car, when have you felt this ? I have felt it in some 996's but whenever I have there has always been air in the system.
Do you feel this right after bleeding still ? If so maybe you should reconsider that bleeding conversation that we had previously.
As for the fluid, I think you will be happy with your race shops advice.
It's better right after a flush and then seems to get worse with use. It's not been like what you get when you boil the fluid. Been there, done that. That's why I switched to SRF. It's just not as firm as I've felt in other cars. Particularly noticeable coming into T10 going CCW at TWS.
This is a source reference. Confirm exact model applicability in the original material.
