|
Most ester based DOT 4 brake fluids will turn dark just by sitting. They are very hygroscopic, meaning they absorb moisture readily and much faster than DOT 3 fluids. It is for this reason DOT 3 fluid is recommended for a street car. The reason being, DOT 3 fluids do not absorb moisture as rapidly, but they boil sooner once they have, making them unacceptable for track use.
The advantage of DOT 4 fluids, such as Motul (and what I use as well) is due to its high boiling point when "wet", meaning after absorbing moisture. The drawback being it absorbs moisture faster and should be changed regularly; more often than the OEM DOT 3 fluid. This is acceptable for a track car where you perform brake bleeds and/or even flushes more often (or should), but on a car that sees only occasional track use may be unacceptable.
Like most everything about a dual use car, it's a compromise.
DOT 4: higher wet boiling point, but requires changing more often, such as when it turns dark, if not before.
DOT 3: absorbs moisture slowly, but boils sooner once it has. Requires changing less frequently.
Last edited by No Doubt : 09-18-2006 at 07:00 PM.
|
