BIG SNIPS

Oh yes.  One other drawback of the phosphate ester oils: They are
hygro-scopic (will absorb moisture out of the air), and the resulting
moisture in the oil will eventually cause it to break down.  I haven't seen
this to be a problem with brake fluids (which really don't get a whole lot
of duty anyhow), but it is a big factor in industrial hydraulic systems that
have a heavy duty cycle.

Doesn't look very likely that we'll have a single all-purpose oil any time
soon!
Tom Kendall

  Tom,

  Thanks for an excellent post.  I have always changed my brake fluid every
24 months.  I spent (misspent?) many of my formative years in FLA, so 90+%
humidity was common.  This makes the water absorption of std brake fluid
(DOT 3) a bigger issue than in a desert environment like Phoenix. After a couple
of years the fluid is translucent gray, presumably corrosion products.  I
have used
DOT 5 (silicone) brake fluid in my Long EZ since '89 with one replacement
of the "perished" (as the Brits so aptly say) O-rings in the calipers.

Bill Freeman

 
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