[johncc]

This was inspired by the other thread about brake discs, brake fluid life, brake pads, etc.

I have an opened bottle of dot 5.1 which I used when I did my clutch. I now want to change a rear caliper, and I'll probably try and bleed new fluid through to all 4 calipers.

Does an opened bottle have a shelf life similar to fluid in the car, i.e. 2 years?

Or less? Or more?

 

[sgould]

I would say a sealed bottle has a longer shelf life. The risk on the car is water absorbtion. Mostly through the vent holes and throught the wall of the rubber flexibles. Your bottle should be OK as long as it's not rubber. The poly or metal is impervious. So as long as you didn't get it contaminated when you first used it, I think it's OK.

 

[ylee coyote]

the hermetic seal was broken so the shelf life will depend on how well the seal on the cap seals

If you used a significant amount then the moisture in the air that is in the void will be absorbed plus any moisture that gets past the cap...

tricky one

how much do you value your life ?

 

[Stephen Brown]

I took a lesson from a long-time DIY mechanic. Buy the smallest new fluid containers you can, use what you have to and throw away ANY opened but unfinished container. The fluid is hygroscopic and there's no way you can stop it absorbing water.
It's the safest thing to do.
I change brake fluid annually, it's a habit now.

 

[cdcarlsson]

Since the bottle is fairly easy to access (well, compared to the caliper end of the brake system ) you could use a garages' fluid tester in the bottle to see how it shows up.

A question though, what is brake fluid? Is it an oil of sorts? I'm wondering how to dispose of it, at a local amenity site.

Nick.