Brake Fluid Freshness

[chefwong]

I see this post now and again....
Just short of knowing that the *retailer* moves his product at a decent pace---fresh brake fluid stock, is there any other compelling reason on judging brake fluid life.

We often reference off that once the *cap* has been removed off a new brake fluid bottle, it only has X days of shelf life. However, all the bottles I've used are not vac sealed .....So is there any sealing to these bottles that I'm just looking at the wrong at ?

 

[INDYMAC]

I just opened a quart of Valvoline DOT 3 today. It had an aluminum seal, so I assume they should all have seals if it's a new container. Since it absorbs moisture rapidly, I wouldn't use it if it doesn't have a seal.

 

[brianl703]

If it doesn't have a seal and you bought it at Wal-Mart, someone might just have put their old brake fluid in that container and returned it for a refund.

 

[byez]

possibly the seal is under the lid? every container i have ever opened had a seal on the bottle though

 

[chefwong]

Brain ----....I forgot there was the seal. ;-)

 

[oilboy123]

They always have foil seals on the ones I buy. Even the cheap ones.

 

[mechtech2]

Once the seal is removed, all is not lost.
The cap gives a very good seal when tightened properly.
There is an almost unmeasureable amount of water in the air in the bottle, but I wouldn't worry about it.
It's just that in the future the history of an opened bottle will be forgotten. How old? was it left opened? Any contaminants?
But if you are sure or your storage, don't worry about it when talkig about a year or two.

 

[surfstar]

Good. I'm gonna start doing a MC drain and refill with the oil changes now. Any particular brand better at mixing with older fluid? I'm assuming its just DOT 3 in there from the last brake flush 2 years ago.

 

[Drew2000]

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Good. I'm gonna start doing a MC drain and refill with the oil changes now. Any particular brand better at mixing with older fluid? I'm assuming its just DOT 3 in there from the last brake flush 2 years ago.

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FWIW, I think changing the M/C fluid every oil change is a waste of time. There is viturally no mixing of the fluid in the system. If you are doing a system flush every two years at the calipers and/or pistons, you should be golden.

I like the Valvoline Syn-Power DOT3+4 fluid myself.

Drew

 

[lobo11]

Okay, some people on the forum do the turkey baster method with their brake fluid as well, others claim you are doing nothing when you do this as it does not mix. I figured what the heck and basted and refilled with fresh this weekend since the fluid is not that expensive. I am sure I am not experiencing a placebo effect, it seems like the brake pedal response is much firmer with the new fluid. I am going to ask my wife if she noticed anything different while braking on her way to work today and see what she says. I guess if she confirms I will be converted to a master cylinder brake baster like some on the forum. Thoughts?

 

[brianl703]

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There is viturally no mixing of the fluid in the system.

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There is. Every time you press the brake pedal, the fluid moves down the line. Every time you release the brake pedal, all of those molecules of fluid plus whatever else is in the line (water and other contaminates) do NOT return to their original position. The molecules in a liquid are free to slide around and move like that. So every time the brake pedal is pushed there is movement of fluid throughout the system, which results in the fluid "mixing".

This is why the fluid in the reservoir does not stay clear.

 

[Drew2000]

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There is viturally no mixing of the fluid in the system.

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There is. Every time you press the brake pedal, the fluid moves down the line. Every time you release the brake pedal, all of those molecules of fluid plus whatever else is in the line (water and other contaminates) do NOT return to their original position. The molecules in a liquid are free to slide around and move like that. So every time the brake pedal is pushed there is movement of fluid throughout the system, which results in the fluid "mixing".

This is why the fluid in the reservoir does not stay clear.

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What ever slight mixing of the fluid that may occur, it is mediocre solution vs. a proper system flush.

Petroleum pipelines move batches of gasoline/diesel/home heating oil/jet fuel etc. over hundreds of miles in pipelines far larger than a 1/4" brake line with no physical speration between the batches and almost no mixing occurs, except at the seperation point of different product.

If the turkey baster thingie makes you feel better, knock yourself out, but is no subsistute to a proper flush, and no manufacturer recomends this method.

Drew

 

[Aldaris]

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If it doesn't have a seal and you bought it at Wal-Mart, someone might just have put their old brake fluid in that container and returned it for a refund.

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you can tell the difference between new and used brake fluid homie

 

[eljefino]

There's a tiny slit in the top of the master cylinder piston that allows the overflow reservoir to drain into the in-use portion of fluid. This is covered by the piston when the brake is depressed. If you have a leak, pumping your brakes helps because when the pedal is at top new fluid dribbles down.

If you have a two-hole kitchen sink, and set up a hose from one to the other as a siphon, fill them both, then put food coloring in one sink, the other sink won't get coloring despite their "connection". Same as the turkey baster fluid change.

That stuff will turn black though, as that cheap plastic reservoir is the least air-tight part of the brake system. So changing the fluid every couple of years will help a very small amount, as the picoliters of fluid the system will accept due to pad wear will then be fresher fluid.

In short, bleeding from beginning to end is the way to go. A good bleed will refill the reservoir FIVE times... a baster at the beginning to start off fresh then four refills after each wheel cylinder is done.

 

[99TA]

I've used the turkey baster method for years on everything,brakes,power steering etc and have had excellent results.Its not near as good as a complete flush but its certainly better than doing NOTHING.

 

[Al]

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I've used the turkey baster method for years on everything,brakes,power steering etc and have had excellent results.Its not near as good as a complete flush but its certainly better than doing NOTHING.

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Be careful with turkey basters. I used a clear baster from WalMart on brake fluid and the brake fluid started deteriorating it in a very seconds. That can't be good.

 

[moribundman]

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I've used the turkey baster method for years on everything,brakes,power steering etc and have had excellent results.Its not near as good as a complete flush but its certainly better than doing NOTHING.

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Cause I want it all
Or nothing at all
There's no where left to fall
It's now or never

 

[brianl703]

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Petroleum pipelines move batches of gasoline/diesel/home heating oil/jet fuel etc. over hundreds of miles in pipelines far larger than a 1/4" brake line with no physical speration between the batches and almost no mixing occurs, except at the seperation point of different product.

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That is a totally different situation. That line is under pressure. The pressure is what keeps the fluids from mixing.

Similarly, when public water supplies lose water pressure, that can allow contamination back into the water supply. That's why they tell you to boil the water after the pressure is restored, until the lines are flushed.

The brake fluid in your brake lines should only be under pressure when you're stepping on the brake pedal.

 

[brianl703]

Incidentally, based on what I've been reading about "diffusion", which is the "random thermal motion of molecules in all phases of matter", even if you never press the brake pedal after changing the fluid in the reservoir it will all eventually mix.

 

[moribundman]

In case of my car, the fluid in the calipers is always the darkest. The fluid in the reservoir and in the brake lines is always clear. This indicates that whatever makes the fluid dark and cloudy (wear particles, heat?) remains pretty much contained in the calipers.