Brake fluid recommendation?
 

Hi. Recently my brakes ended their life (both disks and pads) and when I heard quote for replacement OEM Brembo disks and pads both me and Subaru dealership/workshop I service my car in decided that f*ck this sh*t I'm out. They recommended me DBA Xtreme Performance slotted disks and pads that go with them instead. They looked fine and price was good so I decided - why not. I always wanted slotted disks anyways.

Unfortunately today, during some more intense testing, my brakes went off almost completely - definitely thermals related issue since when I gave them a break (heh) for a while they got back to normal but then when I started hammering them again, they started to fade away again. I'm not entirely sure what's at fault - it could be pads but considering they have optimal operating temps up to 550°C and disks start to glow at 400°C I'm having quite hard time believing that I was able to reach such temps during street driving (sure, I'm on TW 50 tires and I was really beating those breaks quite hard with multiple 160-0 kph but still it sounds quite unlikely).

So my blind guess is that it could be brake fluid. Since well I'm on some generic crappy OEM Subaru brake fluid and brake cycles to 0, frequent in hard city driving tend to be quite harsh for breaking fluid since you stand still on hot brakes and I heard that it may result in brake fluid heating up and boiling.

So what are your recommendations in the field of brake fluids? Sorry for TL;DR but I wanted to give some context just in case my reasoning is severely flawed at some point and it couldn't be brake fluid.

any dot 4 fluid will work.

there's racing fluids that will achieve higher temperatures, but you really shouldn't need that.

If you lost breaking and had a solid peddle then it is brake pad related. If you had your peddle go to the floor then had to bleed the brakes then it is fluid related.

I suggest you just slow down - :eyebulge:

Pedal felt like sponge. It worked to some very small extent and then when I pushed it to the floor it didn't do much (ABS didn't kick-in despite pedal being stuck in floor and I wasn't being ejected from seat like usually am - breaking force was significantly reduced). I also didn't really feel any smell of burnt pads. Thus I believe it may be related to fluid. I've seen that some crappy brake fluids have boiling points around 250°C which is really likely to be exceeded by my brakes during more spirited driving.

Yep that is fluid related. I change mine with Motul 600 every 6 months when tracking. Never had an issue but I am not the fastest driver ether.

So I'm cosidering Castrol React SRF and Brembo HTC 64T. Castrol seems to have very good wet boiling point so I believe it's more robust and tolerant to crappy fluid replacement job while Brembo has highest dry boiling point.

How likely is it to screw up fluid replacement so badly that it would be below its dry boiling point immediately after replacement? xD I don't have anything against having to replace fluid every 6 months or so together with oil and TW50 tires but I'm a bit worried that replacement process itself would need to be so perfect in order to really hit this Brembo HTC 64T dry boiling point that I'm simply not able to reach that anyways and would be better off with idiot-proof Castrol.

Always been a fan of Motul RBF600. Use it in all my motorcycles. Will probably use it in the BRZ when it's time for fresh fluid.

SRF is nice of course but really pricey. I've never been able to boil the Motul RBF600 fluid on track in either my 86 or my track car. Its pretty cheap so not expensive to keep fresh fluid in the system.

It is possible for pedal to get soft/spongy with the *pads* going off. Old Hawk HPS pads did that to me at the track years ago, I bled and bled and bled but pedal would get soft and even try to go to the floor after a couple of laps! Then I noticed the pads were pretty much gone. Threw OEM pads back in there and the brakes came back!

Anyway, if the change was noticed after changing pads, pads could very well be the issue.

Regarding fluid, name-brand parts store DOT4 or DOT5.1 (*not* DOT5!) is fine for any street application and most track applications. I've gotten better results with OTS DOT4 and 5.1 for street/track than some track-specific fluids I've tried. Never overheated/boiled at the track and last a lot longer between flushes than track-specific, in my experience. I can get through half my track season starting with fresh fluid, then do a caliper-bleed midseason and I'm good for the rest of the year.

I'm happy with ATE Typ 200 - it has good wet (388) and dry (536) boiling temps and is pretty cheap (typically under $20 for 1 liter). Serves me well on the street and the handful of track days a year. I change the fluid every year in the spring ahead of the first track event.

Anecdotal, but ATE 200 is one that for me underperformed relative to parts-store DOT4. Had to bleed after one day at Watkins Glen in the S2000. Next event went back to either Castrol or Pennzoil DOT4 and it lasted three 2-day events, with the car co-driven at one of them, without any bleeding.

More recently I had a race shop working on the car flush/bleed brakes on the BRZ (w/ Brembos) before an event with Motul (RBF600 I think). Same thing! 2nd day at the track, had to bleed calipers.

Never any issues with parts-store DOT4/DOT5.1 making it through at least three 2-day events.

Again, anecdotal, and frankly mystifying, but easy and cheap enough to just run what works best for me...

I had the same result with ATE. RBF600 was fine for me though but I am just buying name brand DOT4 at the parts store anymore and not having any issues.

https://www.northstarmotorsports.com...duct4/5649.jpg ?