[Spridgets] What fluid for clutch master cylinder?

[Dean Hedin]

Larry Daniels  > "It can all be summed up thusly:
Silicone is for boobs, not brakes."

Hah! Wrong. It's great in boobs and it's great in brakes. 
One thing for sure, they will never make glycol filled breast implants.

And guess what...This discussion isn't over...its just getting started.

As Guy points out, there seems to be a misconception that silicone fluid is
incompatible with the rubber parts in the brake system.

Here's a typical data sheet for DOT 5...
http://www.clearcoproducts.com/pdf/specialty/NP-dot-5-brake-fluid.pdf

Notice the statement 

"DOT 5 Silicone Brake Fluid is compatible with a wide range of brake
materials including SBR, EP, Neoprene and Natural Rubber."

More importantly "Meets MIL-PRF-46176B"
You can download that spec here : http://tinyurl.com/43agjha

In a nutshell that spec states that the fluid is not allowed to swell a
standard SAE "SBR Test Cup" (wheel cylinder seal) more than 1.4mm.

This "1.4mm swell" is the same standard applied to non silicone fluids. 
as described here: http://tinyurl.com/3wn9372

So there you have it, DOT 5, safe on paint and safe on rubber.

Silicone has been known to swell boobs though, sometimes drastically.