Brake fluid shelf life in unopened containers

[ryan2022]

Hi guys,

I've got two bottles of brake fluid I bought today in the small 1/2 quart containers or whatever they work out to be.

They're unopened and will stay this way until I use them for a flush.

What is the shelf life for unopened bottles of brake fluid? Is storing it in an unheated garage over the winter okay?
Thanks,

Ryan

 

[VK56VD]

Are the bottles plastic or metal? I hear brake fluid in plastic bottles absorbs moisture through the bottle itself. The longer it sits, the more moisture it will absorb.

 

[ryan2022]

Yes, theyre plastic. They will be 8 months old when I sue them.

I wonder about putting them in a large zip lock bag.

 

[benjamming]

8 month old new brake fluid is nothing harmful

 

[ryan2022]

Thanks,

I wasnt too worried, just wondered if Id shot myself in the foot.

 

[JHZR2]

it sits under the hood in many folks' cars for 5-10 years...

 

[Tones]

Yah, but after all that time it certainly isn't what it was when it started and should have been replaced already

 

[Hootbro]

Originally Posted By: Spartuss
Are the bottles plastic or metal? I hear brake fluid in plastic bottles absorbs moisture through the bottle itself. The longer it sits, the more moisture it will absorb.


The plastic is not porous and will not absorb moisture though it. That would defeat the purpose of packaging it in plastic bottles to begin with.

 

[tom slick]

It depends on what plastic they use. technically most inexpensive packaging plastics, namely PE and PP, are not air barriers. how much air/moisture that will be absorbed over what amount of time is the question.

I have no issue using brake fluid that is a couple years old if it's been in a closed plastic container.

 

[Boomer]

Unless the container is made of metal, there will be a Water Vapor Transmission (WVT) value associated with the plastic barrier. This can be made very low but it is still going to be a finite value. IMHO, I would discard unopened brake fluid after about two years and buy fresh. I would never buy too much at one time but just enough to do the job at hand. When you buy fresh, but it from a store like an auto parts house that has HIGH turnover.
Foam insulations made of plastics for very low temp refrigeration pipes have to be specially formulated to resist (but not eliminate) the movement of water vapor through the foam's closed cell walls. Specialty materials are added to help with this. These are expensive and I doubt that such materials are added to brake fluid bottles.

 

[benjamming]

For racing applications, I would agree Boomer. However, for the everday Joe (or Jane) the brake fluid in their system may be 10 years old. In addition, we have no idea of the bottled date on any brake fluid.

 

[HTSS_TR]

My friend's 1991 Honda Accord had factory filled brake fluid until last year when he changed it before sold the car. The fluid was black and had a lot of dirt in the reservoir. Somehow the brake system never failed. When I had my cars at local mechanic for some services, I saw most cars in that shop had black brake fluid in reservoir, those owners never changed their brake fluid. When the shop owner recommended changing brake fluid, the car owners asked why change it if the brake system still working ?