Shelf Life of Brake Fluid - opened vs. closed

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In your opinion....what is the shelf life of brake fluid

- open in sealed tin can
- closed in plastic bottle
- open in plastic bottle

Just curious how long I can keep/use the latter in it's respective applications. I use ATE 200, Motul RBF600 and Castrol SRF. Cars using Motul and SRF get fluid chaned frequently. Street cars using ATE 2 years...1 year if I have time.


Just curious what is the longevity of shelf life in open or unopen applications..
 
I would think that factory sealed, it should be good for a few years. Open and tightly closed in Florida humidity (where I live) would be about a year in plastic or metal containers. I write the date I opened it on the bottle. Brake Fluid is pretty inexpensive, so I dispose of it properly after roughly a year, since it will absorb humidity and moisture (I forget the tech term for it).
 
In a tin can, a long time, maybe indefinate. In plastic 5 years according to Castrol. Open can; I would agree on a year or so. I'm not as anal about open containers as I used to be. Shop I used to go to had it kept in a one gallon tin can with a hole punched in the top of the can to allow the pump to pump out the fluid.
 
Once it is opened, you have cut it seriously. use a little and close it tightly in a dry climate, fine. Every time you open it to look at it or take out a drop, you let humidity in.

Want to play?
In a humid climate, open a bottle and just leave the top off. it will overflow by the next day. That is water being absorbed that reduced the boiling point and makes it thicker.

I frequently see 5 or 6% in problem systems, but once it hits 25% the fluid is so thick it is hard to pump.
 
Go figure....for those that are participating in this thread I'm going to assume you may follow similar brake flush schedules like I do....


I take brakes and tires very seriously...

And then there is the majority which I had to guess probably not have flushed their system in 6 years...
 
Originally Posted By: chefwong
And then there is the majority which I had to guess probably not have flushed their system in 6 years...


...or my brother, who has not flushed, nor changed his in 11 YEARS!!! (In his daily driver/beater)
crazy2.gif
 
Originally Posted By: Deltona_Dave
Brake Fluid is pretty inexpensive, so I dispose of it properly after roughly a year, since it will absorb humidity and moisture (I forget the tech term for it).


I believe hygroscopic is the term you are looking for.

And the italicized part of your post indicates that you most definitely are NOT a Castrol SRF user!!
 
I have a lot of unused fluid after replacing all the hard lines on my car. That fluid wasn't touched for 10 years. It was nasty.

Good to know the fluid I buy on the shelf is still in okay shape.
 
The stuff in your car's plastic reservoir is good for two years so IMO an opened container with the lid on is good for at least that long.

Since it turns brown/black as it ages, compare the bottle to the reservoir. If it's more clear, you're improving things by adding it. (Though any off tint would have me chuck it.)
 
Originally Posted By: eljefino
The stuff in your car's plastic reservoir is good for two years so IMO an opened container with the lid on is good for at least that long.

Since it turns brown/black as it ages, compare the bottle to the reservoir. If it's more clear, you're improving things by adding it. (Though any off tint would have me chuck it.)


two years in the car as long as you look at it through the plastic, not taking off the top to "see better". But in the car the air you close in is a few ml.

In the bottle, if it is half full, you are locking in 6 ounces of moist air that will be absorbed. if you then open and take out an ounce, you are locking in another 7 ounces of moist air.

As one guy once told me: "This is a great product. Each week I top off my brake fluid and the bottle never empties."
 
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