Can you preserve opened brake fluid?

[zerosoma]

Decided to change my brake fluid this morning as well (did the trans last night), but only used part of the big bottle I bought.

I immediately put tin foil over the top (several layers) as soon as I was done and then replaced the cap and put tin foil over it.

Will this help from moisture getting in?

 

[eljefino]

I'd get the foil out from under the cap. It might have a better seal without interference, some rubbery or papery stuff in there.

 

[Rand]

how much did it cost?

regardless since its open its good for about a year usually then toss it.

 

[HerrStig]

It's important stuff, not worth trying to save a buck on.

 

[SLCraig]

I would keep it for a while, but when it starts to get all old and dust covered it's time to just replace with new.
I always just buy small bottles even if they are a bit more, because you tend to only use one small bottle at a time when doing a brake system repair like a caliper replacement, etc.

 

[zerosoma]

Ha, yes. I bought this for around $8, it's the Valvoline stuff. I just hate wasting stuff, and my manual says to not keep open brake fluid because of moisture.

The cap went on pretty tight and I was able to screw it on over the tin foil. Hopefully it keeps well?

 

[ahoier]

Honestly, how often does one "top off" the brake fluid? I know I don't.....I change it, when I change my brakes, and that's it.....I never need to top it off....I'd say just dispose of it......no point trying to save a couple bucks....it'll likely be contaminated by the next time you need it (2+ years? unless you do a lot of driving and change the fluid a lot....)

 

[JHZR2]

If you can get parafilm, that might work OK. But to save it, id want it saved in a dessicator or a very dry, cold environment.

 

[cutter]

I'd imagine the seal at the cap is just as good as the seal on the reservoir. Heck, my reservoir just has a rubber boot of a cap instead of a screw on.

 

[dparm]

This is why I prefer to buy several small bottles for a buck or two more. The big bottles are fine if you're doing two cars at once.

 

[Teddi]

I wouldn't mess with the foil - just screw the cap down gorilla tight. If you're really OCD, maybe teflon tape on the cap threads and store in a dry area such as a dehumidified basement.

 

[HTSS_TR]

Originally Posted By: cutter
I'd imagine the seal at the cap is just as good as the seal on the reservoir. Heck, my reservoir just has a rubber boot of a cap instead of a screw on.

I agree.

Many 10+ year old vehicles have original brake fluid without problem. Brake fluid in an opened container with the cap tighten well and stored in a cool dry place should be able to use after 3-4 years.

 

[SOHCman]

I was just considering buying the smaller valvoline brake fluid when I noticed it was roughly half the price, it didn't look like half the volume though so it's likely more per fluid ounce. Probably worth the peace of mind.

 

[dailydriver]

Originally Posted By: JHZR2
If you can get parafilm, that might work OK. But to save it, id want it saved in a dessicator or a very dry, cold environment.


^^^This is what I do with my leftover RBF 600, and even with brand new, unopened bottles.
I put them in doubled-up ziplock bags, with a BIG bag of that car interior dessicant which Griot's used to sell.

 

[mechtech2]

We have to have water or moisture directly present for the brake fluid to absorb any.
One little trick is to squish the bottle or can so there is less air [with potential moisture] in it before replacing the cap.

Brake fluid is not a black hole voraciously sucking water.
It is not the IRS for water.
It is not a puppy at the food bowl.