[TR] Using Opened Brake Fluif

[Randall]

> I seem to recall that you shouldn't use an opened container of brake fluif
> because there may be water in it from condensation. The bottle I have was
> first opened about a year ago. Fact or old wife's tale?

Fact, although not quite as stated.  Conventional (non-DOT 5) brake fluid is
hygroscopic, meaning it will act like a desiccant and actually suck water
from the air.  No condensation required.

The "wet" fluid is both more likely to boil inside the brakes (giving you
instantly no braking at all), and more corrosive to brake components
(especially rear wheel cylinders on a TR, with steel piston against an
aluminum bore).

This process continues with the fluid in the car, which is why it should be
completely replaced, from a freshly opened container, every 2-3 years.  

Note that this process will also continue until the fluid contains far more
water than the amount used for the "wet" boiling point given in the DOT
specifications.  In a paper presented to the SAE, they claimed the average
water content in the 3 year old cars they tested was 7.5%; while the "wet"
boiling point is given with 0.5% water.

Randall