Topic: Silicone brake fluid, what experience have you had with it?

[C5ZZ]

Last summer I installed the brakes on my 65. Put on new
wheel cylinders, hoses, brake lines etc and used silicone
brake fluid in the system. The car is still work in progress
so it hasn't moved since I installed the brakes. I was just
under it and noticed both front tires are wet at the bottom
and there is a drip at the bottom of the backing plate.
It seems to be coming from inside the drum, probably the
wheel cylinders. I did a little research online and have read
that some rubber brake parts are not compatable with silicone brake fluild.
Looks like I'm going to have to redo the brake job and possibly
switch to standard brake fluid.
Any one else have this happen to them?
If so what did you do?

[67gta289]

I put it in my 67 Mustang (front disc) in 1981 when I rebuilt the whole system with standard off the shelf rubber boots and seals. The complete system was purged of old fluid first.  The lines were all original steel.  Absolutely no problems that I attribute to the fluid.  One of the original front hoses blew out in 2005 and the original rear hose in 2006, which I attribute to age not the fluid, as the outside rubber was dry rotted and split.  Car sat for long periods (years) at times.  Did not do periodic bleeding. The car is being reworked, and I plan on going back to silicone based on the good experience.  I'm interested in other experiences also. John

[Bob Gaines]

I put it in my 67 Mustang (front disc) in 1981 when I rebuilt the whole system with standard off the shelf rubber boots and seals. The complete system was purged of old fluid first.  The lines were all original steel.  Absolutely no problems that I attribute to the fluid.  One of the original front hoses blew out in 2005 and the original rear hose in 2006, which I attribute to age not the fluid, as the outside rubber was dry rotted and split.  Car sat for long periods (years) at times.  Did not do periodic bleeding. The car is being reworked, and I plan on going back to silicone based on the good experience.  I'm interested in other experiences also. John

+1 . different cars and dates but the rest is the similar. Bob

[CharlesTurner]

I've had good luck with silicone, exclusively use it on show cars.  Have had it in drivers with no issues.

[Murf]

I have been using silicone brake fluid, more commonly known as DOT 5, in Mustangs for 20 or more years with no problems.  In fact the product is used to prevent problems, and it certainly has prevented them for my cars.  Used to have to rebuild the four piston calipers on the early Mustangs often, and always found that one of the pistons was leaking out of the four.  As you know, moisture caused sludge and pitting of the iron in the calipers and the wheel cylinders due to the conventional brake fluid having the ability (disadvantage really) of absorbing moisture.  Silicone does not have this ability and just simply prevents moisture from getting as far into the system as conventional fluid did.  The use of silicone requires a clean and fresh system, and you will still have to flush and replace the silicone every two or three years to keep your system working well.  Yes, there are disadvantages to using silicone, and it is certainly a tragic mistake to use it with ABS type brakes on newer cars. but it is for me a life saver in our collector cars.  I hope you rebuild or replace your faulty components, flush your system well with denatured alcohol and give the DOT 5 one more chance to help you keep your brakes working well.  You will find tons of material written about DOT 5 fluid and helpful hints, but simple quality rebuilding of brake parts and fluid replacement every two or so years normally nets good results and prevents catastrophic brake failure on cars that are seldom driven and sit for extended periods of time. 

[cobrajetchris]

I have had silicone brake fluid in one of my cars for 20 years and never had a problem. On the other hand I have had the conventional dot 3 fluid ruin some of my paint work on my firewall when the master cylinder decides to leak (and it will). Before you know it it looks like someone poured paint stripper down the side of the firewall underneath the master cylinder. I would bet you just have a defective wheel cylinder and not the fluid, Especially if all the other hoses and wheel cylinders are OK. 

[C5ZZ]

***UPDATE***

I had a chance to check into my leak problem
and the fluid is indeed leaking from the new
wheel cylinders that I had installed last fall.
I'm thinking the the rubber components were
not compatible with the silicone fluid causing
the leak which is on both fronts. I bought a
new pair of wheel cylinders from NAPA, the
description says they are compatible with
silicone fluid so I will change them out in the
next few weeks and that should take care of it.

Thanks for all the help!

[C5ZZ]

***another update***

finally had a chance to install the new NAPA wheel cylinders, also
installed new copper washers that seal the hose to the wheel cylinder,
all ok so far.