Re: Silicone brake fluid

[Bill Ballon <bmwbill@xxxxxxxxxxxxxx>]

Silicone brake fluid sellers have used this disinformation to sell it for
years.
The best advice on silicone fluid is to never use it!

>I pulled this off of a product description from a supplier and remember this
>is quote, not my opinion:

Absolutely NOT true!
>>"DOT 5 silicone brake fluid is the best brake fluid that you can use in
your 
>>automobile. 

Another lie. Silicone brake fluid was developed for the military for use in
Arctic stored
military vehicles.  The fluid doesn't have as large of a viscosity change
like conventional 
glycol based fluids, so it was thought that the Silicone would perform
better in those conditions.
It is interesting to note that the military has spent millions of dollars
removing the stuff in
the last several years as well.

>>This fluid was originally developed for racing because of its much higher 
>>boiling temperature 

The non-hydroscopic aspect of silicone allows the moisture that inevitably
enters the system to
become more concentrated in "pockets" low in the brake system.  This causes
MORE corrosion and 
creates an even higher potential for the brakes to boil since the buffering
effect of conventional
brake fluid is not there.  If any conventional brake fluid is left anywhere
in the system, the interface
where the old fluid and Silicone meet will be prone to corrosion at that
point with even more severity.      It also allows the moisture in the
system to freeze if temperatures are below freezing.   The 
conventional brake fluid's affinity for moisture allows the moisture to be
absorbed into the fluid
to suspend it inside the system rather than allow it to concentrate in the
system and cause far 
more serious problems.  The Bosch Automotive handbook warns against
Silicone brake fluid on
page 235.  It also points out another deficiency in that silicone brake
fluid has poor lubricating 
properties as well.

>>as well as not being hygroscopic ( it
doesn't abbsorb moisture >out of the air) .

Silicone brake fluid is five times more compressable than conventional
brake fluid.  It also
has a higher viscosity, which can cause slow release of brake pressure
through the return port
in the master cylinder and even greater malfunction in ABS equipped cars.

>> Silicone brake fluid creates a firmer pedal feel and is compatible with 
>>all types of braking systems."

The info that you are referring to here is the correct info.
>Everything that I have heard about Silicon fluid is exactly opposite in
>regards to pedal feel and compatibility with brake systems where standard
>fluid was used.  Does anyone have more information either way.  I agree that
>it does not absorb moisture and does have a higher boiling point, but I have
>heard that the brake pedal actually gets softer and it sometimes goes to the
>floor at the most inopportune times???

>I use ATE blue, but a friend was interested in silicon.  I know some people
>with old cars (trailer queens) that do not drive them regularly use it.

Bill Ballon

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