In a message dated 2/23/00 9:27:25 PM Eastern Standard Time, microdoc@apk.net
writes:
<< Compressibility? Of a liquid? If such a thing could occur, I seriously
doubt one
could detect it with a foot.
> And 3. the above seal swelling problem.
I respectfully suggest this is a myth. If the stuff is no good I'd appreciate
some proof before I remove what appears to be perfectly performing, 10 year
old,
anhydrous brake/clutch fluid, and replace it with rust-worm food. >>
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Dr. Jim,
Here is the info from the Vintage Triumph Register on DOT 5. I am not
advocating that you rush out and replace your brake fluid with DOT 4,
especially since you have had no problems for 10 years.
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"Advantages:
DOT5 doesn't eat paint.
DOT5 does not absorb water and may be useful where water absorption is a
problem.
DOT5 is compatible with all rubber formulations. (See more on this under
disadvantages, below.)
Disadvantages:
DOT5 does NOT mix with DOT3 or DOT4. Most reported problems with DOT5 are
probably due to some degree of mixing with other fluid types. The best way to
convert to DOT5 is to totally rebuild the hydraulic system.
Reports of DOT5 causing premature failure of rubber brake parts were more
common with early DOT5 formulations. This is thought to be due to improper
addition of swelling agents and has been fixed in recent formulations.
Since DOT5 does not absorb water, any moisture in the hydraulic system will
"puddle" in one place. This can cause localized corrosion in the hydraulics.
Careful bleeding is required to get all of the air out of the system. Small
bubbles can form in the fluid that will form large bubbles over time. It may
be necessary to do a series of bleeds.
DOT5 is slightly compressible (giving a very slightly soft pedal), and has a
lower boiling point than DOT4.
DOT5 is about twice as expensive as DOT4 fluid. It is also difficult to find,
generally only available at selected auto parts stores. "
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I can only gather info from whatever sources are out there, and then make my
choice based on that info. I have read most of the above info from multiple
sources, including other's experience on this list. As I have said on this
list before, read the advice and take responsibility for your own decision
about which course of action you will use. Experience is the greatest
teacher, and not everyone who contributes in this open forum is an expert.
Considering your experience and what Barney has said, I would say that DOT 5
is certainly a usable brake fluid. I chose Castrol LMA because I didn't want
to take a chance on any of the above problems in my car. That does not mean
I would have those problems, I just didn't want to take the chance.
Use whichever fluid works for you. I don't think anyone recommends using the
same brake fluid for 10 years, but an annual flush and refill should prevent
most problems and unless outside factors cause a leak, you may not have to
rebuild anything in that time.
Allen Hefner
SCCA Philly Region Rally Steward
'77 Midget
'92 Mitsubishi Expo LRV Sport
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