Bill,

   Did you mean "DOT 5" fluid? 

   DOT 4 is borate-ester/glycol based, and is compatible
with (but a higher flashpoint than) DOT 3 automotive brake
fluid.

   DOT 5.0 is silicon based; and DOT 5.1 is borate-ester/
glycol again, but more borate and less glycol for *boiling
point* similar to DOT 5.0.

   BTW, although DOT 5.0 won't harm paint, it will render any surface it touchs *unpaintable*.

Regards,
Dale

Yes Dale,

 Sorry on the typo. Yes silicone fluid is "dot 5". I personally don't like the silicone fluid as it becomes slightly compressible at high temps. It is compatible with any seal meterial I've ever encountered though. Matco brakes says auto fluids are no problem so you could use any type you like. I have heard of at least 4 aero brake fluid fires with people I know or have met. It does present problems. Durring my racing years 0 brake fluid caused fires. even with disks covered in fluid when debris broke hoses.

Bill Jepson