Low viscosity brake fluid only ??

[Olgeezer1]

I see that BMW recommends only low viscosity brake fluid for all late model cars. As far as I can tell that limits me to ATE SL6 or Pentosin Dot4LV (which I'm guessing is the factory fill). Both have identical boiling points ( 509/338 ). While my car is 90% street driven I thought a higher temp. fluid like Motul 600 would be great for the odd track day that I do as long as there's no downside. Apparently the downside is when cold, ( street) the thicker fluids do not work well in the tiny ABS/DTC passages in our cars and can cause a mushy pedal and delayed response in an emergency stop. Not good. Plan on adding the Performance brake kit from BMW to deal with the increased heat of track days but curious about this fluid issue. Any informed comments would be welcome.

[_Ryan_]

I don't run low viscosity fluid. My brakes work, nothing feels "great" without a few turns and stops each drive, but I've never had an issue stopping in winter.

Turner cover this on their website.

[John_01]

Motul RBF600 works really well in our Australian climate. I don't know about Canada, but why not try it in the middle of winter and do some testing to check. I'm using ELF Dot 5.1 fluid now which is thinner viscosity, but I'm not sure if its really an upgrade or not.

Where did you hear that Motul Dot 4 brake fluid causes a mushy pedal in low temps?

[Olgeezer1]

John_01 Look at Turner Motorsports site for their comments. Also the ATE SL6 site for the same type of comments. Both say there is a delay in emergency response time. My car is summer driven only so cold temps. are not really an issue. Ideally, it'd be Motul for track days and back to LV fluid for the street but realistically I know I'm not going to do that. While I imagine I could use the higher temp. fluids I'm thinking at this point to stay with the recommended LV fluids for a 90% street driven car. Thanks for the comments.

[_Ryan_]

Originally Posted by John_01

Motul RBF600 works really well in our Australian climate. I don't know about Canada, but why not try it in the middle of winter and do some testing to check. I'm using ELF Dot 5.1 fluid now which is thinner viscosity, but I'm not sure if its really an upgrade or not.

Where did you hear that Motul Dot 4 brake fluid causes a mushy pedal in low temps?

In Sydney[NSW], sure. In the hills of Vic, I tend to follow the Canadian trends

The turner stuff is here-
http://www.turnermotorsport.com/t-br...fferences.aspx
http://www.turnermotorsport.com/BMW-...ake-fluid.aspx

Originally Posted by TMS

The BMW DOT4 ESL brake fluid is a low viscosity formula for modern ABS and DSC systems. BMW recommends low viscosity brake fluid for all chassis beginning with the E60 5-series. Low viscosity (LV) is a thinner fluid that works better than a normal fluid in the small channels and passageways in the ABS/DSC pump. Using the heavier fluid will result in a delayed response to ABS and DSC activation and a spongy feel in the brake pedal (only during ABS stops). BMW ESL is a DOT4 rated fluid and is compatible with other DOT3 or DOT5.1 fluids. For track use, a heavier high performance brake fluid such as Ate Typ 200 or Motul RBF600 or RBF660 is recommended because of their higher boiling point and because the thicker fluid will thin out at track temps. But for street use we recommend switching back to a LV fluid, especially in colder climates.

Oh, and my comment relating to "nothing feeling great" was to provide context as to my tolerances.

[slonik]

Motul RBF600 works really well in our Australian climate. I don't know about Canada

600 and 660 works excellent here in russia, on 25-30 below zero (celsius)

[MightyMouseTech]

Interesting.

ATE makes a special LV fluid SL-6. At -40 is has a viscosity rating of 700.

http://www.ate-na.com/www/ate_us_en/...f_info_us.html

Type 200 has a rating of 1400.

Castrol SRF has a rating of 1300.

http://msdspds.castrol.com/bpglis/Fu...57C0700407627/$File/BPXE-9CPEPF.pdf

I am currently using Honda Motorcycle Racing DOT4. May have to switch.

[jaye944]

Low viscosity brake fluid can be used in vehicles that do not require a low viscosity fluid; however, standard DOT 3 or 4 brake fluid should not be used for top off in vehicles that require a low viscosity brake fluid. This action will reduce the low temperature properties and decrease the safety performance of the fluid.

Originally Posted by Olgeezer1

I see that BMW recommends only low viscosity brake fluid for all late model cars. As far as I can tell that limits me to ATE SL6 or Pentosin Dot4LV (which I'm guessing is the factory fill). Both have identical boiling points ( 509/338 ). While my car is 90% street driven I thought a higher temp. fluid like Motul 600 would be great for the odd track day that I do as long as there's no downside. Apparently the downside is when cold, ( street) the thicker fluids do not work well in the tiny ABS/DTC passages in our cars and can cause a mushy pedal and delayed response in an emergency stop. Not good. Plan on adding the Performance brake kit from BMW to deal with the increased heat of track days but curious about this fluid issue. Any informed comments would be welcome.

[jaye944]

use exactly what BMW recommend, end of !