Quote:
Originally Posted by Inthepasture
Just an fyi, page 205 of the manual specifically says to not use DOT 5 fluids
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Correct, "DOT 5"
DOT 5.1 is not DOT 5. 5.1 is compatible with DOT 3/4 where DOT 5 is not. DOT 5.1 is a better fluid and what we used when I was into sportbikes as it has a lot higher boiling point over DOT 3.
Not to be confused with
DOT 5, a
silicone based fluid.
DOT 5.1 is one of several designations of
automotive brake fluid, denoting a particular mixture of chemicals imparting specified ranges of
boiling point.
A brake fluid's dry boiling point is the temperature at which the pure fluid will boil. Wet boiling point concerns the boiling temperature when the fluid contains water.
In the United States, all brake fluids must meet Standard No. 116; Motor vehicle brake fluids.
[1] Under this standard there are three
Department of Transportation (DOT) minimal
specifications for brake fluid. They are
DOT 3,
DOT 4 and DOT 5.1.
DOT 5.1, like DOT 3 and DOT 4, is a
polyethylene glycol-based fluid (contrasted with
DOT 5 which is
silicone-based). Polyethylene glycol fluids are
hygroscopic and will absorb water from the atmosphere, which is necessary to prevent sheer and undiluted water in the braking system,[
citation needed] which is very corrosive, also water droplets can freeze in the pipes, thus blocking the system.
DOT 5.1 is the non-silicone version of DOT 5, defined by FMVSS 116 as being less than 70% silicone. Above that threshold makes it DOT 5.
Contents
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Boiling points[edit]
Minimum boiling points for these specifications are as follows (wet boiling point defined as 3.7% water by volume):
Boiling point ranges [2]Dry boiling pointWet boiling pointDOT 3205 °C (401 °F)140 °C (284 °F)DOT 4230 °C (446 °F)155 °C (311 °F)DOT 5260 °C (500 °F)180 °C (356 °F)DOT 5.1260 °C (500 °F)180 °C (356 °F)