Re: [MV] Silicone Brake Fluid - About Dean's comment.

Richard Notton (
Wed, 20 Oct 1999 05:42:45 +0100

-----Original Message-----
From: dloucks <>
To: <>
Cc: <>;
Date: 20 October 1999 04:32
Subject: Re: [MV] Silicone Brake Fluid - About Dean's comment.

>Okay, here is my experience with silicone brake fluid.

>I started using it 15 years ago when I was autocross racing and would routinely
>cook my brakes. Silicone fluid has very good heat resistance.
But not as good as the latest regular brake fluids.

>Silicone brake fluid is 2% more compressible than glycol-based brake fluid.
>You might feel the difference, I cannot.
It is a very small difference.

>Silicone fluid tends to hold bubbles introduced from pouring more tenaciously
>than standard fluid. Therefore, time should be taken between filling a
>reservoir and bleeding/use to prevent bubbles from entering the lines.
That it most certainly does, using a can that has stood a while and pouring as
gently as possible without agitation is helpful.

>Silicone fluid WILL NOT absorb water, which is what causes the crud to build up
>in wheel cylinders and lines over time.
Not only that but the absorbed water will collect eventually, under severe
stress this can boil making vapour (steam) and lead to total brake failure,
however, when investigated the system will appear to be wholly operational
again. Over here fluid change is a 3yr service item.

Silicone fluid is ideal in older lightly stressed vehicles that stand a lot
provided the seals are compatible with it.

>I convert all my vehicles to silicone fluid and never have any problems.
People with older British MV's should be aware that some are mineral OM13 fluid
(oil) only, FV701's are confusing having been converted from OM13 to "Brake
fluid" in some cases, FV 600 series and FV101 series are definitely mineral
OM13. Using normal fluid in these will have all the seals swell and possibly
disintegrate, theoretically these components were marked with a green splash of
paint, but then the army has re-painted the whole vehicle several times when we
get it.

It is noted that various RR, Jaguar and Citroen vehicles use mineral fluid only.
. . . . . . .

I wonder what bright spark designated the latest regular fluid to be DOT 5.1
whilst the silicone is DOT 5, all the cans of 5.1 here have had to be over
labelled with a warning that it is NOT silicone based.

(Southampton UK)

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