Never use silicone brake fluid. It is strangely and inexplicably compressible, leaving you doing leg presses on the brake pedal to get actuation.

[Kat von Himmel]

I know it is very high-temperature, has GREAT resistance to water invasion, as it is not hygroscopic. that's H Y G R O S C O P I C.

However, bad news, I fond when I eagerly installed it. The brake pedal turned into a trampoline. This weird stuff is compressible.

No, I didn't have air bubbles in the system. It was properly installed.

Fictitious story: I submerged the whole car in a tank of silicone brake fluid, pumped the pedal on all the open bleeders until the fluid coming out of bleeders ((I had to use SCUBA gear) was clear.

Anyway, yes, i bled and refilled the system properly.

This stuff is terrible at the one thing we require of brake fluid: relatively high incompressibility.

So bad, I regard it as a safety hazard to use.

Now, if having 700 degree temperature tolerance and zero water absorption are more needed in your case than actually having any pedal feel, then it may be what you need. I just wanted to save you all a bit of time and money.

 

[Av8ing1]

Silicone brake fluid DOT5 is not great for high performance use. DOT 5.1 might be as it is not silicone based. Worse DOT5 can cause nasty issues when mixed with non silicone fluid. Unless you were replacing all brake system components including lines (or really well flushing them out with air and solvents) I would not use DOT5. It is usually used in classic vehicles that are rarely driven as it does not absorb water it can last a very long time with no need for replacement. Its also expensive so for track guys that will be flushing/replacing fluid anyway it would make no sense. What DOT5 would do with an anti-lock break system...yeah probably not good things. Your going to need to flush that system a bunch to avoid the nasty gunk that occurs when silicone fluid comes in contact with non-silicone fluids. Then a few months later do it again, then again.

I do use DOT5 in my 72 Scout II. Works fine in that application along with complete replacement of the entire brake system.

 

[coolblue]

Very weird stuff. Did a disk brake conversion on my '57 Chevy and used DOT 5 silicon. No problems. Worked perfect. Redid the car and brakes a few years later and used it again. Could not get a pedal or get it to work. Bled system with enough DOT 5 to fill a 5 gal drum(expensive). Had to go DOT 3. Then it worked perfect......????

 

[Jungle Cat]

Spongy is the word.