Do you unused old brake fluid?

Messages
674
Location
Nebraska
I have about 3-4 1/2 bottles of DOT 3 and 4 laying around and I used to keep it for top off, but I bought a brand new bottle to flush my wifes brakes this weekend. I think I will dispose of the old stuff and the new stuff when the flush is done. What do you guys do?
 
Messages
22,732
Location
CA
I don't keep brake fluid in-stock. I buy one quart a time for brake flushes. If there's any leftover in the bottle after a flush, it gets tossed in the trash.
 
Messages
19,528
Location
Lake Forest, CA
I used opened bottle brake fluid within a year or two for top off. I tried to seal the opened bottle brake fluid with plastic over the top then squeezed the cap tight on top of the plastic, this way very little moisture can get in the bottle.
 

rcy

Messages
1,593
Location
Burlington, Ontario, Canada
 Originally Posted By: The Critic
I don't keep brake fluid in-stock. I buy one quart a time for brake flushes. If there's any leftover in the bottle after a flush, it gets tossed in the trash.
Isn't there a hazardous waste depot you can take it to instead of the trash? Maybe the same place you drop off your used oil can take it? I don't keep mine after I open it either, but we have a waste management center (used to be called the dump) that takes HHW (hazardous household waste) free of charge.
 
Messages
309
Location
Gretna, La
first off you shouldnt need to top off brake fluid. If it is low then either your brakes are wearing down to possible replacement or a leak. Both would need immediate attention.
 
Messages
19,479
Location
Chicago Area
What's wrong with topping off brake fluid? You get a fresh shot of clean fluid to mix in with the old, and less air and concurant moisture in the reservoir. If the pads are low or there is a leak, that is another story, but I'd still keep the reservoir filled.
 

Kestas

Staff member
Messages
13,829
Location
The Motor City
The is some merit to Firehawk's comment. On some cars, like my 98 ZX2, the brake fluid level goes down and trips the warning light at about the exact same time that the brake pads need to be replaced. It's done this for the past six times the car wore down the front pads.
 
Messages
768
Location
Portland, Oregon
 Originally Posted By: mechtech2
What's wrong with topping off brake fluid?
Modern master cylinders have seals that keep dirt and moisture out of the system. Every time you take the cap off you allow moisture from the air into the system and potentially allow foreign matter into the system.
 Originally Posted By: mechtech2
You get a fresh shot of clean fluid to mix in with the old, and less air and concurant moisture in the reservoir. If the pads are low or there is a leak, that is another story, but I'd still keep the reservoir filled.
The rubber baffle in the cap should not allow in any air. Clear fluid reservoirs are you friend. Don't open the cap unless needed.
 
Messages
19,479
Location
Chicago Area
Open the brake fluid reservoir cap to add fresh fluid, if needed. Do not drive the car with it off. The few seconds of exposure to air will have zero effect concerning moisture contamination. Zero. If any moisture got in from the seals, or from osmosis through the rubber lines, the fresh fluid is an additional advantage.
 
Messages
2,698
Location
Silicon Valley
You could use the old clean brake fluid as an initial flush next time you change brake fluid. When I do my car I keep flushing until the whole quart is gone, and then I'm done and no leftovers.
 
Messages
5,917
Location
Waterloo, ON
 Originally Posted By: The Critic
I don't keep brake fluid in-stock. I buy one quart a time for brake flushes. If there's any leftover in the bottle after a flush, it gets tossed in the trash.
I would not throw this stuff in the trash, as it will eventually find it's way into our groundater or streams. You can mix it in with your old motor oil and have it recycled
 
Messages
449
Location
PA
I have heard that one way do dispose of old/unwanted brake fluid is to get some kitty litter and put it in an open container. Pour the brake fluid on that and leave it for a couple of weeks. This supposedly allows the brake fluid to evaporate. I am going to conduct a small experiment to see if this actually works... Andrew S.
 
Messages
5,917
Location
Waterloo, ON
 Originally Posted By: dnastrau
I have heard that one way do dispose of old/unwanted brake fluid is to get some kitty litter and put it in an open container. Pour the brake fluid on that and leave it for a couple of weeks. This supposedly allows the brake fluid to evaporate. I am going to conduct a small experiment to see if this actually works... Andrew S.
That's wild...but why do that when it can be re-cycled with your oil. Do you think the evaporation will help with our air pollution problem?
 
Messages
142
Location
Chicago, IL
you do not need to "top off" brake fluid! The level lowers with the brake pads wearing, and comes back up when you put new pads in! Owners manuals specifically warn against toppping off brake fluid! And adding fresh fluid is a null argument, since brake fluid circulates VERY little as it is...
 
Messages
446
Location
York, PA
 Originally Posted By: Bluestream
I would not throw this stuff in the trash, as it will eventually find it's way into our groundater or streams. You can mix it in with your old motor oil and have it recycled
I read somewhere on this forum that brake fluid is alcohol based and should not be mixed with motor oil for disposal. And that has to be true, because I read it on the internet.
 

Kestas

Staff member
Messages
13,829
Location
The Motor City
That depends on what the recycler plans to do with the waste oil. If he sells it to industrial, mixed-fuel burners then it's okay to mix the brake fluid in. If it'll be rerefined, then brake fluid should be kept out. Do the right thing and ask your recycler.
 
Messages
5,917
Location
Waterloo, ON
 Originally Posted By: Kestas
That depends on what the recycler plans to do with the waste oil. If he sells it to industrial, mixed-fuel burners then it's okay to mix the brake fluid in. If it'll be rerefined, then brake fluid should be kept out. Do the right thing and ask your recycler.
I did ask, (SafetyKleen) and they said mix it in. And they re-refine their oils
 
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Messages
5,917
Location
Waterloo, ON
 Originally Posted By: VW_TDI_PD
you do not need to "top off" brake fluid! The level lowers with the brake pads wearing, and comes back up when you put new pads in! Owners manuals specifically warn against toppping off brake fluid! And adding fresh fluid is a null argument, since brake fluid circulates VERY little as it is...
When you change your pads you should open the bleeder screw and let the old fluid go out. That way you are not pushing dirty fluid back into the system.
 
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