Once you open a bottle of brake fluid, if you don't use it all at once, are you supposed to discard it, or can you store it and use the rest later?
The user manual says not to use brake fluid that is not sealed.
There is the risk that the brake fluid might have picked up water over time. This can lead to degassing/boiling of the brake fluid under high temperature conditions, and also leads to corrosion.
If you are not sure that the fluid has not absorbed water, it is a good rule of thumb not to use it. You have too much at risk, and new brake fluid is cheap.
Approximately 9/10/03 08:32, Martin Lynch uttered for posterity:
The user manual says not to use brake fluid that is not sealed.
Oh, you knew that already. Tends to pick up moisture unless you live in Tucson.
|Once you open a bottle of brake fluid, if you don't use it all at |once, are you supposed to discard it, or can you store it and use the |rest later? | |The user manual says not to use brake fluid that is not sealed.
Well, yes and no. Once exposed to air, the fluid absorbs moisture from the air immediately. That moisture content reduces the boiling point. It also hastens corrosion of hydraulic internals.
As a practical matter, if you take great care to only leave the MC and the bottle open to the air for as little time as possible (loosen cap, open MC, open bottle-pour quick-recap both immediately) you are probably OK to save the remaining fluid. If you live in Florida or elsewhere where it's humid, it's a big issue. In Phoenix it is less so. If you are a chronic late-breaker, or you drive mountain roads it's more of an issue, because you get the brakes hotter. Brake fade is no fun, and it always happens when you most need to stop.
The above applies to glycol-based fluids, DOT 3 or DOT 4. Silicone brake fluid is exempt because it is non-hygroscopic..
Rex in Fort Worth
As long as it doesn't turn dark, you can still use it. If you have a plastic brake fluid reservior in your car, any fresh fluid will darken in a few months, even in a dry climate.
That is because brake fluid absorbs water even from humidity.
It isn't worth the risk having any water in the system that can boil under hard braking heat and you loose the pedal for a pump or two.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT'sMart>
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