Brake Fluid - shelf life

indefinitely while sealed

mrcheerful

"mrcheerful ." wrote

I thought so too, but according to motorcyclebloggers.com......

"I recommend buying in pint sizes. This minimizes the wasted brake fluid because it has a shelf life.especially brake fluid in an opened (unsealed) container. Even new fluid that is still factory sealed has a shelf life of about two years"

If it had it would have a 'use by' date on the tin. The one I've just looked at doesn't. And given that many car makers only recommend a twice yearly fluid change while it's in service I find it even harder to believe.

I see that brake pads have a best before date too, likewise cam belts. I would not be frightened of old unopened brake fluid.

mrcheerful

"mrcheerful ." wrote .

FWIW I agree with you and Dave. As far as I can see, so long as the fluid is not in contact with the atmosphere, from where it can absorb water, then it ought to last pretty much indefinately.

You can absorb water through the plastic bottle but it would take decades to have a deleterious effect, unlike the twit in Halfrauds who tried convincing me it went through so fast that the shelf life was only a few months.

I've heard of air going through some types of plastic - which is why you should use barrier types for central heating, but water?

Nylon can absorb something like 40% it's own weight in water if you extrude it wrongly.... Water is a powerful solvent and the molecule is quite small and mobile.

I'm sure some plastics can - but then why would you use them for a bottle of fluid known to absorb water?

Price of course - easier to form, cheaper raw materials, and if it's good for only 10 years rather than 100 it's not the end of the world...

OTOH just buy the brake fluid in a tin bottle - ATE is.