Thanks Ed,

I have been following the discussion and your post prompted me to see what
aircraft brake fluid was all about.  For those who haven't bothered to
google this, Mil-H-5606 is a mineral based hydraulic oil (unlike brake fluid
which is glycol or silicone based) with a flashpoint of 284 degrees
Fahrenheit.  Hmmm, no wonder people have brake fires.  The up side is it is
pretty much the same price as DOT-X.

Anybody have an idea why hydraulic oil is chosen?  I know hydraulic oil is
used in heavy equipment to apply the brakes, I think the simple reason in
that application is that there is a lot of it pressurized and available. I
trust that is not the reason it is used in a C172? -- Ian

P.S. Good Luck Ed!

Do NOT use automotive brake fluid in aircraft brake systems.  Incompatible
with the seal materials.  See information at
http://www.groveaircraft.com/brake_info.html

Ed A