Besides DOT 4 silicone fluid which has the advantage of not harming paint, I have been using various synthetics in my race bikes for years which are good to better than 600°F! I have heard some older auto fluids are corrosive to aluminum but with the number of aluminum components on modern cars it MUST be less common. I have had all sorts of ALUMINUM BRAKE PARTS including master cylinders on my bikes and never seen ANY problem. The aircraft fluid is simply stupid when compared to modern auto fluids.

I think most compatibility problems went away when Girling quit using natural rubber seals and vegetable oil fluids in their products (British cars still stuck in the 30s).

 

Less than a second into serious braking the rotor temps will be well past the 400 Degree flash point of the "New MIL-Spec" fluid.

 

If there were such a problem, you could drop an old seal into a jar of the proposed fluid for several months to see the result. Any Hot Rod shop has fluids in the 550 degree (Lockheed)

to 600+ degree (Wilwood) wet boiling point. Obviously the flash points are well above that, but you could contact the Manufacturers and ask. Just don't mention aircraft.

 

When you see the rotors on the circle track racers flashing to bright orange and spit sparks twice each lap, for 400 miles, does it make you think these boys know about brake fluid. 

 

I have raced with silicone and liked the nonboiling feature. It is difficult to get a good solid pedal because silicone retains air for long time. It is also thick enough that power bleeding with a pressurized master cylinder gives the best result. Power bleeding from the caliper end is also a good method. In any case not moving the master cylinder during bleeding will give better results. All non silicone fluids absorb water from the air at a known rate. If a small amount of that water flashes to steam during braking, the next time the pressure on the pedal is released, the remaining steam pressure will push the fluid back through the master cylinder and leave that system useless.

 

I use the Lockheed 550 and bleed the brakes to new fluid every two races. Never had a brake problem.

 

If you wait for the FAA to figure anything out, you will be too old to fly.

 

Lynn E. Hanover