[BiturboS4] Brake Fluid

Ian Duff iduff at rcn.com
Fri Mar 28 14:15:54 EST 2003

The critical points are wet boiling point, and DOT number. DOT 3 or DOT 4 is
what you want, and NOT DOT 5. www.howstuffworks.com/question451.htm. DOT 5
is typically used in cars that see infrequent use, such as show cars, and is
formulated to not absorb water. It is silicone-based, to achieve this
resistance to water absorption. DOT 3/4 fluid is hygroscopic, which means it
absorbs water over time, hence the measurement of its wety boiling point.
Being hygroscopic also makes it unsuitable for cars subject to prolonged
inactivity. DOT 3/4 is what is traditionally used in street cars subjected
to track conditions. Race use is usually DOT 4, but with a focus on dry
boiling point, since racers typically change brake fluid as frequently as
they change tires.

Motul 600 is an excellent DOT 4 brake fluid, with a wet boiling point of
421oF. Other popular DOT 4 choices include ATE Super Blue and ATE Type 200
Gold, wet boiling point of 392oF, identical except for color, makes flushes
easy. Ford Motorsport makes a popular DOT 3 High Performance Brake Fluid,
with a wet boiling point of 401oF. Folklorre has it that these four are the
best from which to choose. I'm sure there are others of similar quality, I
just don't yet know of them, nor of their suitability. HTH.

-Ian Duff.
-----Original Message-----
From: biturbos4-admin at audifans.com
[mailto:biturbos4-admin at audifans.com]On Behalf Of Ti Kan
Sent: Friday, 28 March 2003 11:43
To: Step88
Cc: biturbos4 at audifans.com
Subject: Re: [BiturboS4] Brake Fluid

Step88 writes:
> I'm getting ready to change the brake fluid in my S4 and I want to make
> e I get the right stuff.  I've heard that the stock fluid doesn't hold up
> ell on the track and should therefore upgrade to something like Motul 600.
>  I've also read that they are not recommended to replace silicone based
> ids, but I can't determine if the stock fluid is silicone based.  Can
> ne tell me if Motul 600 is compatible with the S4 system?  They also
>  to have a couple of different kinds.  Any experience with any of them?

I don't have any personal experience on the Motul so I can't comment,
but the factory fluid is certainly not silicone-based.  You should not
use any silicone-based fluids in these cars.

2003 A4 1.8T multitronic
2001 S4 biturbo 6-sp
1984 5000S turbo
1980 4000 2.0 5-sp
    ///  Ti Kan                Vorsprung durch Technik
   ///   AMB Laboratories, Sunnyvale, CA. USA
  ///    ti at amb.org
 //////  http://www.amb.org/ti/

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