Bob:
DOT4 brake fluid is indeed hygroscopic. That is, it absorbs moisture
out of
the air.
If the DOT4 container was tightly capped after use, it should be just
fine to
use brake fluid from an already opened container. DOT 4 fluid turns a dark
gray or dark brown when it absorbs moisture, so if it is clear and "clean"
looking then it is still perfectly good. You will notice that the old brake
fluid in our cars gets very dark as it absorbs water, and it should be
replaced bi-annually to restore good performance and to avoid rusting brake
parts.
DOT5 is NOT hygroscopic, and never has moisture issues unless it is
somehow
directly contaminated, so it will not go "stale" as DOT4 can. DOT5 has other
problems such as bubble entrainment, cost, and non-miscibility with DOT4 but
in general is a good choice when rebuilding or even doing a complete fluid
replacement. I converted my TR6 to DOT5 three years ago to insure my new paint
did not get puked on. So far, everything has been perfect. I would be overdue
for a fluid change if I had used DOT4 when I restored my car.
Vance
Vance Navarrette
Cogito Ergo Zoom
I think, therefore I go fast
-----Original Message-----
From: 6pack-bounces@autox.team.net [mailto:6pack-bounces@autox.team.net] On
Behalf Of Bob Danielson
Sent: Friday, February 13, 2009 3:54 PM
To: triumphs@autox.team.net; 6pack@autox.team.net
Subject: [6pack] Using Opened Brake Fluif
I seem to recall that you shouldn't use an opened container of brake fluid
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?
Thanks
Bob
Bob Danielson
1975 TR6 CF38503U
Running w/ Throttle Body Injection
Toyota 5 Speed & Nissan LSD
http://tr6.danielsonfamily.org
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