> As I read it, DOT 3/4 and DOT 5 no mot mix.
It's true they don't mix, rather like oil and water. They are fully
compatible, meaning neither harms the other, but don't mix.
> They separate and the DOT 5 does not surround the DOT 3/4.
Purely a personal observation, that the blobs of DOT 3/4 didn't seem to be
stuck to anything, at least not in proportion to how sticky the 'tar' was.
Best comparison I can think of is oil and water again, if you put oil in a
pan and then throw in some water, the water stays separate and sinks to the
bottom. However, there remains a very thin layer of oil between it and the
bottom of the pan, the water does not "wet" the pan and spread out, but
rather forms distinct droplet(s) with curved under edges. If you look
closely at Nelson's "before and after" pictures of his mix, you can see how
in the "before" photo, the edge of the glycol turns up against the jar,
indicating that the jar is 'wet' with the glycol. In the last "after"
photo, the turned up edge (known as a meniscus) is not evident, indicating
the jar is no longer wet with glycol. Silicone has a much lower surface
tension, so the meniscus caused by it doesn't show in Nelson's photo.
http://www.buckeyetriumphs.org/technical/Brakes/Fluid/Fluid.htm
> If DOT 5 does surround the DOT 3/4, how
> the the remaining DOT 3/4 become tarry?
I'm not sure of the exact mechanism, again it's just an observation. But I
know that glycol absorbs moisture from the air and even through rubber brake
lines; and the moisture does eventually cause it to turn dark and
deteriorate. Since it starts absorbing moisture the moment you open the can
(assuming the can was packed in zero humidity, which I doubt), the glycol in
your system already has moisture and so will continue to deteriorate even if
the silicone keeps any additional moisture away from it. I suspect the
glycol also tends to "vacuum up" any debris from seals that wear, etc. and
perhaps even any impurities (like the purple dye) from the silicone.
> [Alcohol is probably the last thing I'd flush the
> system with because it has a boiling point of 175 oF, much lower than
> the water you're trying to remove because of the low boiling point.
Just to be clear, I have the greatest respect for Nelson, his abilities,
knowledge and opinions. That doesn't mean I always agree with him, or that
either of us is wrong when I don't.
To put it another way, opinions are like a**holes : everyone has one and
most of them stink <Grin>
If you go back & read Nelson's page, I think you'll see we agree on that
point :
"(Remember that the internet is free speech, not necessarily accurate
speech, this note included.)"
Randall
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