How long does brake fluid keep in its container?

[Green 912]

I have a true fluid boil point tester and I have been testing a partly used up can of ATE blue from time to time. In going on 7 years it has lost 5 deg boil point. That is about 1%. This can is partly filled and stored in humid condition in the summer.

[Green 912]

Originally Posted by gregwils

I have an unopened (still sealed) can in my garage of ATE blue, I would guess it is close to five years old. Is it still good?

It will cause you cars brakes to explode! Send it to me ASAP and be saved.

[Thrlls]

I flush my brake system once a year, and alternate between ate blue & gold. I use the entire can to flush the system just to be sure the fluid has been exchanged. At $15 a year, this is worth the insurance of having good brakes. I then dump the old fluid into an oil change box to be absorbed and place the box in the trash can.
If I ever have a need to top off the mc, then I have another problem...a leak somewhere, and will need to fix it. So I see no need to store brake fluid for any length of time. The less HM I have stored at my home the better.

[RWebb]

Originally Posted by Green 912

I have a true fluid boil point tester and I have been testing a partly used up can of ATE blue from time to time. In going on 7 years it has lost 5 deg boil point. That is about 1%. This can is partly filled and stored in humid condition in the summer.

- Good to know! Va. is not the driest state in the union, either. Is it in a heated area in the winter?

[911pcars]

FWIW, some brake fluids absorb moisture faster than others. As a consequence, their wet boiling point ratings are lower, as much as 100ºF difference. These particular fluids will have poorer shelf life in partially used containers. You can compare some HD fluids on this chart:

http://www.seinesystems.com/BrakeFluids.htm

Sherwood

[Wayne 962]

I'm not sure how much of this is urban myth versus actually affecting performance. Tony Callas and I had this discussion recently, and we couldn't come to a definite conclusion. We did decide that brake fluid was cheap enough to go the safe route and use new stuff every time. Don't forget that the fluid sits in your reservoir for years at a time - is that to say that the stuff in there is no good? Still probably safest to use new fluid (plus more brake fluid sales for me!)

-Wayne

[Bill Verburg]

I mwouldn't keep fluid in my street car longer than 2yrs, the damage that can be done from trying to extend b/f life is massive and expensive especilly since abs pumps became common

for tracked cars most organizations mandate at a very minimum annual b/f replacement, those cars inflicted w/ undersized brakes that run hotter than desireable will usually need fresh fluid for each event(if not sooner)

It's your money and your car, but it's a shame to see so many misers around, like the o;ld ad says"Pay me now or pay me(more) later"

[javadog]

If you ever boil your brake fluid at a track event (or elsewhere) you'll be an instant believer, that I will guaruntee.

Also, anybody that thinks that Bill is kidding about the damage to hydraulic system components from water contamination of the fluid is invited to spend the summer in Tulsa, rebuilding a bunch of motorcycles I have aquired. ALL of them have issues related to old, contaminated fluid.

Those of you with the new-fangled hydraulic clutches need to bleed those systems too.

JR

[ossiblue]

I use this rule of thumb: I change the fluid every two years in the system, and any remaining fluid in the can is kept only that long also--saved only for top-off's (rare) and then desposed of.

Definite, heed javadog's post, above.

[RWebb]

"massive and expensive" means you may have to replace all the metal lines, and each caliper.

I am a strict 2 year person on my car (street use). Everybody gets to make their own choice.

[hcoles]

yes, for older cars I like to do every year.. come to think of it.. all my cars are old... I now have a full time job maintaining 5 cars.