I don't disagree on the SRF, even tho I run that lol.
which motul...660?
which motul...660?
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Thumbie wroteRealistically it doesn't matter, their plain old DOT 5.1 is sufficient for anything short of big aero race cars. Run whatever flavor makes you sleep better.
which motul...660?
I tried both, neither tasted very good
But in all seriousness...been running SRF for a while. And it works but I would be interested in trying something else. I'll report back what I go with and the differences I noticed. Recently got a quickjack so brake jobs go much faster now.
But in all seriousness...been running SRF for a while. And it works but I would be interested in trying something else. I'll report back what I go with and the differences I noticed. Recently got a quickjack so brake jobs go much faster now.
When I ran the stock system I used Pagid RS29 front and RS19 rear pads with RBF660 and stainless lines. The 660 held up fine, but around the 3rd track event I'd notice the pedal getting softer and needed to bleed the fluid again (about 2-3 months in between track events). RBF660 is glycol-based and pretty hygroscopic, so it's not a fluid you want sitting in your system for long stretches.
Eventually I switched to SRF since it's more street friendly. It's silicone-ester based, less hygroscopic, and reacts chemically with whatever moisture it does absorb. Its wet boiling point (~518F) is the highest of the bunch by a good margin, which is why it holds up so much longer between flushes. The tradeoff was pedal feel, I had to relearn my braking points since SRF is more progressive compared to the strong initial bite 660 gave me.
When I went to a BBK, I switched to AP Radical R4 instead of my usual RBF660. R4 has the highest dry boiling point of the three (~644F) and a noticeably firmer pedal. Its wet boiling point (~383F) actually sits in the middle of the two fluids, so I could stretch the R4 a little longer between flushes than the RBF660. Once I stopped tracking as much, I flushed SRF back in since I daily the car more than I track it now.
Eventually I switched to SRF since it's more street friendly. It's silicone-ester based, less hygroscopic, and reacts chemically with whatever moisture it does absorb. Its wet boiling point (~518F) is the highest of the bunch by a good margin, which is why it holds up so much longer between flushes. The tradeoff was pedal feel, I had to relearn my braking points since SRF is more progressive compared to the strong initial bite 660 gave me.
When I went to a BBK, I switched to AP Radical R4 instead of my usual RBF660. R4 has the highest dry boiling point of the three (~644F) and a noticeably firmer pedal. Its wet boiling point (~383F) actually sits in the middle of the two fluids, so I could stretch the R4 a little longer between flushes than the RBF660. Once I stopped tracking as much, I flushed SRF back in since I daily the car more than I track it now.
- Motul RBF660, glycol based. Dry boiling point around 615 F, wet boiling point around 311 F.
- Castrol SRF, silicone ester based. Dry boiling point around 590 F, wet boiling point around 518 F. Has a higher compressibility, which contributes to that more progressive pedal feel.
- AP Radical R4, glycol based. Dry boiling point around 644 F, wet boiling point around 383 F. Has a lower compressibility, which gives it a firmer, more direct pedal feel.
