Flush brake fluid

[e82n54]

I need to upgrade my brake fluid for a track session so I will be flushing out the old fluid. I have never done this before so I would like to confirm my plans before I screw something up. (Brakes are kind of improtant and I want them to work.) I plan to use Castrol SRF so I don't have to worry about flushing or bleeding the fluid after each event. Since the existing fluid and the Castrol SRF are the same/similar color (I assume), I plan to start flushing with ATE Super Blue to get a different color in the lines. Then flush with Castrol SRF until the ATE Super Blue is flushed out. I read that there is some brake fluid for the traction control system that requires a computer to flush out this fluid. I definitely won't be doing that, so that makes me wonder if that remaining fluid in the traction control system will mix with the Castrol SRF and reduce its effectiveness or boil during the track session even if it doesn't mix with the Castrol fluid. Also, should I flush the clutch fluid to prevent the old fluid from mixing with the new fluid in the master clyinder? I'll be using the Motive pressure bleeder at 10 psi. Please let me know if I should do something different or if I'm forgetting something. Thanks!!

[DriveHard]

You have a good plan.

You do not need to do the super blue stuff first, although i know why you feel you need to . If you put 2 pints of brake fluid in the Motive bleeded, and run that thru the system there is no chance that you will have any of the originnal brake fluid left in the system as the res for the brakes is less than a pint. I would run 2 if not 3 pints of fluid thru the system.

Also, brake res and clutch master res are seperate. BUT you may want to flush that also while you are at it.. I dont think the motive cap fits the clutch master cyl cap as it is alot smaller. You will have to either get the correct cap or do it the old fashion way.

After your first event, just bleed the brakes one more time...not a total flush, this will help with any stuff caught in the system from the abs / dcs control unit. You are correct, unless you connect with disg machine, you cannot activate the abs/ dcs units

[e82n54]

Thanks for the tips.

I'm pretty sure I can flush the clutch through the brake master cylinder. The brake reservoir is separated inside with a brake and clutch section, so I would just flush the clutch as if it's another brake caliper and not move the motive bleeder at all. (That's how I bled the clutch when I changed out the clutch delay valve.)

I don't think I will feel confident without the ATE blue indicator since I've never done this before. Unless there's another way to tell that it's a different fluid.

[fourtailpipes]

why not just use blue and stick with it? then NEXT time go back to yellow. thats what most people (myself included) do.

you're correct about the clutch. bleed like it's another caliper.

[Dackelone]

Originally Posted by fourtailpipes

why not just use blue and stick with it? then NEXT time go back to yellow. thats what most people (myself included) do.

Because some people here have had their dealer void their warranty (or threatened too) bc they saw non oe brake fluid color in the res.


When you use new brake fluid the old fluid will be much darker (brown) in color. New fluid is yellow-ish in color.

[fourtailpipes]

Originally Posted by Dackelone

Because some people here have had their dealer void their warranty (or threatened too) bc they saw non oe brake fluid color in the res.

wow i've never heard that (though it doesn't surprise me)... my dealers are pretty terrible with refusing warranty/maintenance claims, but i've never been asked about my superblue. thanks for the "heads"

[MilehighM3]

Also look into the Motul 600. It's clear, and has a higher boiling point than the Ate super blue. I had some fade, even with different pads, stainless lines and super blue. Changed to the Motul and the issue was gone, same track and same temps. Just a thought....

[e82n54]

I actually asked my service advisor a few days ago if upgrading the fluid would be a problem. He said don't use fluid that's a different color. He also said they could actually test the fluid chemically to see if it's OEM fluid if there's a warranty claim on the brake system. I've also read that ATE super blue stains the reservoir, so I definitely don't want to leave it in. I think I'm just going to play it safe and use the blue fluid as an indicator.

[wolfe]

Originally Posted by DriveHard

Also, brake res and clutch master res are seperate. BUT you may want to flush that also while you are at it.. I dont think the motive cap fits the clutch master cyl cap as it is alot smaller. You will have to either get the correct cap or do it the old fashion way.

Do they definitely have separate caps - It's not one reservoir with a 'dividing wall' inside?

I'm getting ready to do a brake fluid flush too and this would really trip me up if there's a smaller cap that the motive won't fit onto.

thanks


OP - I'm in the same boat. My OEM fluid is a year old and still looks light/clear. I'm switching it for motul RBF600 which is the same color. I thought about using some super blue as a marker too, but in the end I just bought extra fluid to avoid mixing too many types (which I'm sure isn't a problem I just feel better about doing it this way).

[DriveHard]

Originally Posted by wolfe

Do they definitely have separate caps - It's not one reservoir with a 'dividing wall' inside?

I'm getting ready to do a brake fluid flush too and this would really trip me up if there's a smaller cap that the motive won't fit onto.

thanks


OP - I'm in the same boat. My OEM fluid is a year old and still looks light/clear. I'm switching it for motul RBF600 which is the same color. I thought about using some super blue as a marker too, but in the end I just bought extra fluid to avoid mixing too many types (which I'm sure isn't a problem I just feel better about doing it this way).

Im sorry my original post was mis leading ...

our / your cars clutch slave share the master cylinder .... you should be able to bleed as if you were doing the brakes..

sorry for the confusion.. temp brain lapse..

[e82n54]

Originally Posted by wolfe

Do they definitely have separate caps - It's not one reservoir with a 'dividing wall' inside?

There is only one reservoir, which has only one cap. It has a plastic wall inside to separate the clutch fluid. The Motive pressure bleeder for European cars fits this reservoir.

I know Motul fluid would be fine and would not boil, but I think it requires more maintenance than Castrol SRF. I've read that Motul and ATE must be bled or flushed after a track day, but Castrol has a much higher wet boiling point so it doesn't need to be bled after a track day. Since I'll be driving the car home I would rather pay more money for the Castrol to avoid bleeding the brakes at the track or when I get home.

[Focusedintntions]

Everything I've read about the motul fluid says it's fine after a track day...just flush it every 6 months or so.

[pixelblue]

I use motul 600. Flush once a year with 6-7 track days a year. Never had to bleed after or before a track day and never had any problems although I hear castrol is the best you can get so I may try it out next year

[Xaeryan]

Try the Motul or ATE before you spend the money on Castrol. I'm 6 (hot) track days in, with no signs of fluid boil on ATE. Even if I flushed twice during the season, that's still far less than a single Castrol flush.

Since I bring my gear to the track with me (including a MityVac), I won't be flushing until I need to - it'd be nice to find out a rough time frame of when the boiling point comes down to wet temperatures. So far, it's looking like a seasonal flush is all that's required...

[fourtailpipes]

Originally Posted by Xaeryan

Try the Motul or ATE before you spend the money on Castrol. I'm 6 (hot) track days in, with no signs of fluid boil on ATE. Even if I flushed twice during the season, that's still far less than a single Castrol flush.

Since I bring my gear to the track with me (including a MityVac), I won't be flushing until I need to - it'd be nice to find out a rough time frame of when the boiling point comes down to wet temperatures. So far, it's looking like a seasonal flush is all that's required...

i'd been doing superblue about 2x-3x a year when i was seeing tons of track time, and it always came out looking pretty good. now that i'm down to like 3 weekends a year, an annual flush is all i need.

[MilehighM3]

Originally Posted by Scuderia000

I actually asked my service advisor a few days ago if upgrading the fluid would be a problem. He said don't use fluid that's a different color. He also said they could actually test the fluid chemically to see if it's OEM fluid if there's a warranty claim on the brake system. I've also read that ATE super blue stains the reservoir, so I definitely don't want to leave it in. I think I'm just going to play it safe and use the blue fluid as an indicator.

Warranty will not/can not call for fluid. There's lots of regs on fluid transport. The blue will stain, no matter how long it's in there, it won't go away. Fluid transport/ hazmat regs prevent transport of used fluids without serious paper work and cost. Same as airbags, warranty will call for them to be deployed and disposed of. Too much of a hazard to transport... Your advisor is full of it if he says warranty will do chemical tests on old fluid!

[fourtailpipes]

Originally Posted by Bmw135er

Warranty will not/can not call for fluid. There's lots of regs on fluid transport. The blue will stain, no matter how long it's in there, it won't go away. Fluid transport/ hazmat regs prevent transport of used fluids without serious paper work and cost. Same as airbags, warranty will call for them to be deployed and disposed of. Too much of a hazard to transport... Your advisor is full of it if he says warranty will do chemical tests on old fluid!

i have had a dealer test my fluid for its boiling point (there's a basic test they can administer). this wasn't to see if i was using aftermarket fluid, though... it was diagnostic to see if it was being significantly compromised, since they had just flushed it and i came right back for another brake job. just be warned that at least some dealers do have the technology...

[Dackelone]

Back when I use to do a lot of track days and we (a friend of mine) raced in the SCCA's ITb class... we used Ford's H.D. brake fluid DOT4. Laugh if you want but the specs of that stuff was better than almost anything else around. AND it was dirt cheap. We also used AP's 550 brake fluid - but that stuff was more $$. But the problem with AP's (or any other racing) brake fluid is the wet boiling point is kind of low and it attracts moister faster than OE brake fluid. Corosion is not good with todays ABS and traction control systems. BLLED YOUR BRAKES!

So.... IF you run a racing brake fluid... change it often - atleast twice a year. More often if you do HPDE or races.


For US cars BMW says to change the brake fluid every two years. Over here, BMW AG says to change the brake fluid every year.

When a German takes his car to the German safety inspection place (TUV) they take a small sample of brake fluid out and put it in a little heating device that measures the point at which the fluid boils. Your car MUST pass this test. This is a good idea.


For the street I use a German DOT4 brake fluid from my indi parts place over here - Stahlgrube: Car Technic wet boiling point - 165'C and dry boiling pont of 265'C.







Does anyone know what the specs are for BMW's OE brake fluid? The stuff that the dealer sells? I bet its made by either ATE or Castrol.


Dackel

[wolfe]

Originally Posted by DriveHard

Im sorry my original post was mis leading ...

our / your cars clutch slave share the master cylinder .... you should be able to bleed as if you were doing the brakes..

sorry for the confusion.. temp brain lapse..

Awesome, I appreciate the clarification - nothing worse than having the car all jacked up and realizing I'm missing some tools. Thanks for the info.

[e82n54]

Originally Posted by Dackelone

But the problem with AP's (or any other racing) brake fluid is the wet boiling point is kind of low and it attracts moister faster than OE brake fluid. Corosion is not good with todays ABS and traction control systems. BLLED YOUR BRAKES!

So.... IF you run a racing brake fluid... change it often - atleast twice a year. More often if you do HPDE or races.

For US cars BMW says to change the brake fluid every two years. Over here, BMW AG says to change the brake fluid every year.

Dackel,

Castrol SRF is considered a racing fluid, but it has a high wet boiling point. Are you suggesting that this fluid be changed at least twice a year? Castrol recommends changing it every 18 months.

[Dackelone]

Originally Posted by Scuderia000

Dackel,

Castrol SRF is considered a racing fluid, but it has a high wet boiling point. Are you suggesting that this fluid be changed at least twice a year? Castrol recommends changing it every 18 months.

Then follow Castrol's recomendations. I realy can not say one way or the other. I would still go with BMW AG's recomendation of yearly brake fluid changes though.

I do think IF you are going to track your car... you should be flushing the brake fluid and changing the engine oil before each event. I think that is just basic mantainence (& commen sense) for track cars. Besides... when you start to pull off wheels and do the brake fluid flush... you are liable to discover a small problem that could develop into something big. Afterall... it is YOUR life on the line.

[e82n54]

Thanks Dackel. You are always quick to respond with helpful info!