Adam Ligon wrote:
Also unless you plan to bleed/flush the brakes every 2 months look at the wet boiling pts, not the dry. After 2 months in your system the fluid is "wet".
Part of the inspection procedure is to have fluid less than 90 days old. I have never heard the two months to wet but did find this from GS610:
Quote:
How fast does brake fluid absorb moisture?
It depends on the fluid and environment. A typical high performance DOT 4 fluid like, Motul, AP, Castrol SRF, Wilwood and ATE SuperBlue, in a high humidity environment will absorb as much as 4.5-5% moisture in as short a period as 2 weeks. In real world testing (several daily driver cars, GS610 absorbed <1% moisture in 3 years. This was measured from the brake fluid in the reservoir where the vehicle's brake system is most likely to contain the greatest contamination of moisture.
and this from Ryder fleet services:
Quote:
Standard brake fluid absorbs water over time. On average, in two years it's saturated: it's collected enough moisture to warrant replacement, otherwise hydraulic system parts - including costly ABS components - may suffer internal rust damage. Also, "wet" brake fluid boils more readily than when it's fresh.
Most telling, is
http://www.brickboard.com/FAQ/700-900/BrakeFluidComparison.htm
and in particular
Since wet boiling point is 3.5% water (according to the FMVSS), 2 months is probably not truly wet fluid.
However, this is not to say that Adam is wrong. Far from it. While our track procedures say any fluid 90 days or newer is OK, if the data above is right, that fluid is going to have a boiling point lower than the dry one. How much lower? Well, Wes, Scott or some other chemist can figure that out. Adam's rule of thumb, while cautious, does show the truth - that fluid gets wet quickly (it is designed to do so, btw). Me, I'll stick with fresh fluid that is about 90
hours old when I go onto the track.