Ferrari Mailing List: >anybody using silicon brake, , fluid? What is your experience of this?

[Bill Rosen (razpootin]

First and foremost, WELCOME BACK F-LIST!!!

Dennis said,
"...DOT 5 (NOT DOT 5.1!) brake fluid is silicone-based, is not hygroscopic, and
should never be mixed with DOT 3, DOT 4 or DOT 5.1. DOT 5.1 has the same
boiling point as DOT 5, but is not silicone-based. (Interestingly, DOT 5
fluid will not damage paint.) Restoration shops like to use DOT 5 because
the show queens they produce usually just sit, or else are driven on and off
trailers, possibly on nice Sundays. DOT 5 does not need to be changed as
frequently, because it's not hygroscopic, so it's one less maintenance issue
for them.

...The number one reason NOT to use DOT 5 silicone is because
it can provide a slightly mushy pedal feeling..."

<snipped parts unrelated to my comments>

One point that I do not understand relating to DOT5, is that some people (not here) 
have claimed that because the silicone fluid is non-hygroscopic, moisture will collect,
at the bottom of calipers or slave cylinders, beneath the fluid.  I have a difficult 
time trying to imagine this, because:

1) Silicone fluids, at least AFIK, are heavier than water.
2) The only conceivable way for moisture to enter the system, would be through the 
master cylinder resevoir, then refer back to #1.   

I first started using the DOT5, for preservation of old cylinders (prevention of corrosion),
and the lubrication/preservation of rubber seals.  I have never experienced any negative
effects, (spongy pedal or premature boiling) but have never used my cars/bikes beyond a 
level of very spirited street driving.  I am, by no means, an expert in the field of brake 
fluids, so if anyone has any satisfactory explaination for the water being heavier than 
the silicone, I would surely like to hear it. 

Regards,
Bill Rosen