[s-cars] Speed Racer wannabe

[Theodore Chen]

AP600 is not a DOT5 fluid.  it doesn't have a DOT rating as far as i
know.  it's intended for competition use.  also, DOT5 generally refers
to silicone-based brake fluids, which are unsuitable for motorsport use.
DOT5.1 has similar temperature requirements to DOT5 but the DOT5.1 fluids
aren't silicone-based.  DOT5.1 fluids are required to be compatible with
DOT3 fluids, which essentially means they have to be glycol-based like
DOT3 fluids.

AP600 is a borate ester and it is NOT compatible with any other fluid,
including AP550 (polyalkylene glycol ether base).  if you want to use
this stuff, you must flush your system with alcohol several times, and
then with AP600.  borate esters don't get along with glycol-based
fluids like the DOT3/4 fluid that's probably in your car right now.
if combined, they'll form a crystalline precipitate that will require
a complete teardown and rebuild of your brake system.  i'm also not
sure AP600 will work with ABS systems, either.

castrol SRF is a silicone ester.  the specs are incredible: boiling
point at 500 degrees _celsius_, low viscosity, high lubricity, doesn't
absorb water or air, doesn't entrain air when pouring.  but it's tough
on seals, even viton.  just about all cars use nitrile rubber, and
it (along with silicone fluids) can leach the plasticizers out if
it gets hot enough.  oh yes, and it costs $75/liter.

the can may say it's good for a year, but it's just talking about the
fluid itself, not what it does to your seals when it gets hot enough.
note that castrol SRF doesn't absorb water - but water may still get
in, and pool in the low points in your system, which is why periodic
flushing is still recommended.

i'd treat this stuff with caution.  pro race teams use it, but they have
bigger budgets and they replace the seals frequently.  if you have lots
of money and time, and you love wrenching on your car, go ahead and use
the SRF.  but why do that, when motul 600 costs much less and works so
well?  i've never managed to boil fresh motul 600.  it's the best of
the many different DOT3/4/5.1 fluids that i've tried.

valvoline synthetic 5.1 is a good budget alternative, and may be suitable
for your purposes.

we had a brake fluid discussion on s-cars some time ago.  chris miller
archived the thread:
http://members.aol.com/c1j1miller/brake.html#Brake%20fluid

-teddy

--- TM <t44tq at mindspring.com> wrote:
> Teddy-
> You sure about that? I never saw any warning about mixing SR-F with
> anything else. AP600 is a DOT5 fluid which is incompatible with anything
> else, never heard that about SR-F.
>
> Also, about being corrosive toward seals, why does the can say it's good
> for 1 yr. in the system, then?
>
> Taka
>
> -----Original Message-----
> From: Theodore Chen [mailto:tedebearp at yahoo.com]
> Sent: Thursday, September 12, 2002 5:37 AM
> To: TM; 'Bill Mahoney'; s-car-list at audifans.com
> Subject: RE: [s-cars] Speed Racer wannabe
>
>
>
> --- TM <t44tq at mindspring.com> wrote:
> > 2. Do a full brake and clutch bleed with good brake fluid- I'm using
> > Ate Super Blue, I'd also recommend Motul 600 or Castrol SR-F.
>
> the castrol SRF is $75/liter.  it's also not compatible with DOT3/4
> glycol-based fluids.  it's also corrosive toward seals, if you get it
> hot enough, which seems to be the whole point of the exercise. i'd go
> with the motul 600 or the ATE.  i've used motul 600 for years.
>
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