how long does a opened quart or gallon of dot 3 brake fluid last?

[tiredguy]

Hi

how long does a opened quart or gallon of dot 3 brake fluid last?

I have some that are about half full that were opened about 10 years ago. Should I toss them or use them. I would drop it off at the household hazardous waste center.

If it matters humidity wise my location is the SF bay area

 

[The Critic]

I usually toss after a few months. After all, it is a fluid that gets replaced every 2-5 years.

 

[edyvw]

Hi

how long does a opened quart or gallon of dot 3 brake fluid last?

I have some that are about half full that were opened about 10 years ago. Should I toss them or use them. I would drop it off at the household hazardous waste center.

If it matters humidity wise my location is the SF bay area

Same as in a vehicle. Brake fluid change interval is time-based.
Try to sell it to the Russian military on ebay

 

[tasch72]

if you want an objective answer you can buy a brake fluid testing pen off ebay for $3 shipped that will tell you exactly how much moisture is in the fluid. New fluid should have 0% moisture and fluid containing 4% or more moisture should be flushed in a car.

but for 10 year old opened brake fluid I would take it to an HHW. it's cheap enough that it isn't worth the liability.

 

[KevinMalone]

Hi

how long does a opened quart or gallon of dot 3 brake fluid last?

I have some that are about half full that were opened about 10 years ago. Should I toss them or use them. I would drop it off at the household hazardous waste center.

If it matters humidity wise my location is the SF bay area

ATE says the shelf life is up to 5 years in a sealed can so 10 years open is definitely a no go.

 

[4WD]

I usually toss after a few months. After all, it is a fluid that gets replaced every 2-5 years.

And often partially replaced - just ordered genuine Mopar for that reason + Mopar electric steering pump fluid - C note gone … (2+2 small bottles) …

 

[daves87rs]

Toss

 

[D60]

I've gone multiple years in my arid climate where most people survive on a steady diet of Chap Stick or similar.

In a humid environment I'd be more concerned.

And 10 years is too much, even for me. Brake fluid is still relatively inexpensive despite somethingnomics.

 

[edyvw]

ATE says the shelf life is up to 5 years in a sealed can so 10 years open is definitely a no go.

View attachment 243115

ATE packaging is better than others. So, there is that.

 

[GMBoy]

Brake fluid pulls moisture from the air so an opened bottle will start to start absorb water. With the relative cost of brake fluid vs the risks I toss an opened (but sealed) bottle after 2 months. I have a nice digital brake fluid tester and testing bottles 2 months old that were open (but in a sealed container) read 1-2% moisture FWIW.

 

[D60]

Brake fluid pulls moisture from the air so an opened bottle will start to start absorb water. With the relative cost of brake fluid vs the risks I toss an opened (but sealed) bottle after 2 months. I have a nice digital brake fluid tester and testing bottles 2 months old that were open (but in a sealed container) read 1-2% moisture FWIW.

Does it read zero when you first cut the foil?

If it's been cut but the cap is properly tightened I struggle to believe much gets in past the cap vs a new bottle with seal intact.

Supposedly the plastic bottles breathe to an extent, which is part of the argument about old motor oil oxidizing -- if I understand the argument(s) correctly.

Point being, I wonder if it has much to do with breaking the seal vs just breathing through the bottle over time?

What little data I could find suggests Dallas' average humidity is 60-70%. My area is allegedly 44% average with June -- often our hottest month -- at 25%

From what I saw when I watched those idiots on reality shows in Texas, it's far more common to see a car sitting around in a field with heavy body cancer down there. Here, you mostly get that surface patina and then it just stops.

 

[edyvw]

Does it read zero when you first cut the foil?

If it's been cut but the cap is properly tightened I struggle to believe much gets in past the cap vs a new bottle with seal intact.

Supposedly the plastic bottles breathe to an extent, which is part of the argument about old motor oil oxidizing -- if I understand the argument(s) correctly.

Point being, I wonder if it has much to do with breaking the seal vs just breathing through the bottle over time?

What little data I could find suggests Dallas' average humidity is 60-70%. My area is allegedly 44% average with June -- often our hottest month -- at 25%

From what I saw when I watched those idiots on reality shows in Texas, it's far more common to see a car sitting around in a field with heavy body cancer down there. Here, you mostly get that surface patina and then it just stops.

You already allowed mositure to get in. During opening, did you damage cap and threads? There are too many unknowns. When I open the brake fluid, it is tossed out if I end up with extra fluid, which I have to do as a pressure pump needs some extra fluid to work. When I tracked BMW regularly at HPR east of Denver, I changed fluid 2-3 times a year and always tossed out extra fluid. On track, even the slightest drop in boiling point can have an effect.

Also, TX is flat. Considering the clown show, I see every winter on I70 going downhill toward Denver, good brake fluid is imperative.

 

[Ausfahrt]

Brake fluid is one of the few things that I don't try to buy in bulk. Even with preventive measures like working on my brakes on low humidity days, moisture gets in and there's no way to get it out.

I buy small containers and toss what I don't use that day.

 

[Urshurak776]

I'll be honest. I bleed brakes a little bit when I do a break job, and also turkey baste fluid out of Master Cylinder and replace it, but I have never done a full brake fluid replacement.

I typically work alone, and the few times I get my wife to push the brake pedal is hell......

How often do you all change out the brake fluid? I have had vehicles 10 years or more without doing it (other than what I mentioned above.)

What is best way to do this if working by yourself?

 

[GMBoy]

Does it read zero when you first cut the foil?

If it's been cut but the cap is properly tightened I struggle to believe much gets in past the cap vs a new bottle with seal intact.

Supposedly the plastic bottles breathe to an extent, which is part of the argument about old motor oil oxidizing -- if I understand the argument(s) correctly.

Point being, I wonder if it has much to do with breaking the seal vs just breathing through the bottle over time?

What little data I could find suggests Dallas' average humidity is 60-70%. My area is allegedly 44% average with June -- often our hottest month -- at 25%

From what I saw when I watched those idiots on reality shows in Texas, it's far more common to see a car sitting around in a field with heavy body cancer down there. Here, you mostly get that surface patina and then it just stops.

You bring up a good point about the moisture content when first opened. I never checked but I should. I also read may years ago about moisture getting thru plastic bottles as well but not sure how much actually does. I also can't say how much gets in every time we open the bottle for a top off so that is why I keep bottles fresh and under 2mos old.

 

[tasch72]

I'll be honest. I bleed brakes a little bit when I do a break job, and also turkey baste fluid out of Master Cylinder and replace it, but I have never done a full brake fluid replacement.

I typically work alone, and the few times I get my wife to push the brake pedal is hell......

How often do you all change out the brake fluid? I have had vehicles 10 years or more without doing it (other than what I mentioned above.)

What is best way to do this if working by yourself?

brake bleeder and vacuum pump kit

buy a brake fluid test pen, change fluid when it has 4% or more moisture content

 

[Ausfahrt]

I'll be honest. I bleed brakes a little bit when I do a break job, and also turkey baste fluid out of Master Cylinder and replace it, but I have never done a full brake fluid replacement.

I typically work alone, and the few times I get my wife to push the brake pedal is hell......

How often do you all change out the brake fluid? I have had vehicles 10 years or more without doing it (other than what I mentioned above.)

What is best way to do this if working by yourself?

There are speed bleeders on the market that work well. Buying a good one can get pricey but you get what you pay for.

After 30 years of marriage to a shade tree wrencher, my wife knows the routine.

 

[tiredguy]

I plan to flush the brake fluid this weekend.

Just curious would a vehicle with brake fluid that is at 4% moisture have a soft spongey pedal?

 

[tasch72]

I plan to flush the brake fluid this weekend.

Just curious would a vehicle with brake fluid that is at 4% moisture have a soft spongey pedal?

no, that would be air in the lines