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Old opened can of brake fluid still OK to use?

Muse

Muse

Lifer
My Mazda 626LX '97 4cyl coupe could use some brake fluid. The manual says use Dot 3 fluid. I have an old can. It's old. I mean, this thing could be from around 1993. It says Quaker Supreme Super Heavy Duty, Dot 3 brake fluid. I'm guessing the steel can is ~45% full. The outside of the cylindrical 32 fl. oz. can is somewhat rusty, but I imagine the inside is fine. It's by Quaker Supreme Chemical Corp. Would it be dumb to use this or should I just top up with it? The car's got 25,700 on it.
 
If you use it, your brakes will fail (from boiling fluid) when you need them the most.

And, of course, you're going to recycle it.
 
I have a tightly sealed container of opened brake fluid that I keep in my closet (so it doesn't sit outside where it's damp hot/cold fluctuations. You guys think it's safe to use?
 
chucky2 said:
I have a tightly sealed container of opened brake fluid that I keep in my closet (so it doesn't sit outside where it's damp hot/cold fluctuations. You guys think it's safe to use?
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Who the hell keeps brake fluid in a closet?,no, buy a fresh unopened can..
 
Srsly u gaiz?

A quart of brake fluid is $6.60 - $8 at autozone and will do 2-3 brake fluid flushes. Like everyone has said, don't be dumb. Old brake fluid can boil under heavy use and the moisture it has absorbed will also corrode your braking system from the inside out.
 
Unless you're bleeding your brakes, there should never be a reason to need brake fluid. As the brakes wear, the excess fluid in the reservoir will gradually go down. When you replace the brakes, the fluid will go back to the maximum amount.
 
When I had my shop a bottle of brake fluid opened was only kept for 1 month. If it was not used in that 1 month time frame it went out.
 
Jimzz said:
When I had my shop a bottle of brake fluid opened was only kept for 1 month. If it was not used in that 1 month time frame it went out.
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Alright guys, I'm convinced it would be ridiculous to use the old fluid. I'll bring it to a place that does fluid recycling along with my old oil from my change from ~10 days ago, maybe today.
 
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DrPizza said:
Unless you're bleeding your brakes, there should never be a reason to need brake fluid. As the brakes wear, the excess fluid in the reservoir will gradually go down. When you replace the brakes, the fluid will go back to the maximum amount.
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Here's what it says in the owner's manual (exact quote):
- - - -
The brakes and clutch draw fluid from the same reservoir.

Inspect the fluid level in the reservoir regularly. If it's low, add fluid until it reaches MAX. It should be kept at MAX.

Before adding fluid, thoroughly clean the area around the cap.

The level normally drops with accumulated mileage, a condition associated with wear of brake and clutch linings. If it's excessively low, have the brake/clutch system inspected by an Authorized Mazda Dealer.
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- - - -

My reservoir's level looks to be 1/2 way between LOW and MAX. What it says in the manual is why I figured I should add enough fluid to bring the level up to MAX. The car's got ~25,700 miles on it, is about 15 years old, probably has never had the brake fluid changed.

I had my transmission fluid replaced at my local Mazda dealership a few months ago. I'm surprised they didn't check the brake fluid and power steering fluid levels and top them off. They gave me a sheet of paper designed to convince me that they'd taken care of me 100% top drawer, dozens of things ticked off, checked. I'm very unimpressed with them, TBH. I paid a pretty penny. Besides my brake fluid being 1/2 way between the MAX and LOW indicators, the power steering fluid level in the reservoir is right at the LOW indicator. 🙁
 
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Muse said:
Here's what it says in the owner's manual (exact quote):
- - - -

- - - -
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Owner's manual is dumb. They're just covering their asses.

I should check and see if mine says that (also Mazda).

The level tends to be around the 'min' mark (most makes) when the front and rear brake pads are both >75% worn. If you add fluid to max, then get the brakes done, the reservoir is going to end up full to the cap, with brake fluid on the ground (or whatever it drips on after it pukes out the cap).
 
phucheneh said:
Owner's manual is dumb. They're just covering their asses.

I should check and see if mine says that (also Mazda).

The level tends to be around the 'min' mark (most makes) when the front and rear brake pads are both >75% worn. If you add fluid to max, then get the brakes done, the reservoir is going to end up full to the cap, with brake fluid on the ground (or whatever it drips on after it pukes out the cap).
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Uh, so you're saying I should maybe just let it be. My brake fluid level is mid-way between LOW and MAX. I don't think I'm in need of a brake job.

However, my power steering fluid reservoir is at the LOW marker, I guess I should top that up??? 😕 Comments?
 
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Muse said:
Uh, so you're saying I should maybe just let it be. My brake fluid level is mid-way between LOW and MAX. I don't think I'm in need of a brake job.

However, my power steering fluid reservoir is at the LOW marker, I guess I should top that up??? 😕 Comments?
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Slurp out what's in there, refill, cycle the steering back and forth a few times, slurp out the fluid, and refill again. This will replace a lot of your steering fluid.
 
I bought a mityvac kit for flushing brakes and power steering fluids on my cars. $140 well spent considering I've already flushed the brakes on two cars and and the power steering on another. It's paid itself off 2-3x already and still has years of life left. Makes flushing the fluids kinda fun.
 
OILFIELDTRASH said:
I bought a mityvac kit for flushing brakes and power steering fluids on my cars. $140 well spent considering I've already flushed the brakes on two cars and and the power steering on another. It's paid itself off 2-3x already and still has years of life left. Makes flushing the fluids kinda fun.
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I would never do that with a track/race car though. I've never had good luck with the power bleeders; the pedal just never felt right compared to brakes bled the old fashioned way.
 
One other note about brake fluid. Don't shake the container! I once reprimanded a tech for shaking the brake fluid container. When you do this you put air bubbles in the fluid. Guess why he had trouble bleeding the brakes.
 
Preventing air contaminants in anaerobic systems is why some manufacturers eliminated dipstick level-checking of automatic transmission fluid...sealing the system allows the chemistry to stay "fresh" and stable longer...as long as their 100k mile warranty.
 
tonyfreak215 said:
I would never do that with a track/race car though. I've never had good luck with the power bleeders; the pedal just never felt right compared to brakes bled the old fashioned way.
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Well the vacuum bleeder kind are pretty bad about air getting back into the bleeder after you pull the hose off. I swear even trying to close the bleeder with vacuum still on and I have bad luck with them. Any time I ever have to use one to flush the fluid I just accept I'm gonna have to bleed it with the pedal after I'm done. Does speed things up if its a big system or the fluid is just mud.

The fancy bleeders like the one BG makes that put pressure to the master usually work great. The only two screw ups I ever see with those is people put too much pressure to the master, or try to use it on a master thats too old; the seals in the master blow out and they get to put a part on for free.
 
Vacuum bleeders dont introduce air into the system. It will not bleed air out as well as the pedal method if air has been introduced by changing a caliper or whatever.
 
JCH13 said:
I recently tried gravity bleeding my Miata, worked pretty well.
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Gravity bleeding is the bees knees. Especially if the air is only at the end of the line (usually from caliper or brake hose replacement). I usually only need a helper for replacing master cyls and the like.

Also, pressure bleeding > vacuum bleeding. I gotta get around to picking up an assortment of reservoir cap adapters for my 'bug sprayer.'
 
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