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#1
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Brake Fluid Shelf life
Here's a question for you. How long can brake fluid sit in an unsealed bottle before it becomes unusable?
The reason I ask this is because I replaced the brake fluid on one car last weekend and I want to do another car this weekend. I have about half of one of those 1 quart bottles of fluid left over from the last job that I'd like to re-use. It's been sitting in the bottle with the cap on all week and I'd hate to waste it. I'm already familiar with the hygroscopic properties of glycol-based fluids and the warnings about always using fluid from a sealed container, so you don't have to explain that part to me again, thank you.
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"It's not about how fast you can go, but how well you can go fast." Bob in Richmond '97 S320 (LWB), Ruby Red Metallic, 73k miles '97 S420V, Smoke Silver Metallic, 155k miles |
#2
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I'm pretty sure it doesn't go bad...
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Current cars: 2000 ML55 AMG, 174k miles 2003 C240 T-Modell, 202k miles 1995 S320, 207k Miles |
#3
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Once the inner seal on the can is broken, about 2 years.
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MERCEDES Benz Master Guild Technician (6 TIMES) ASE Master Technician Mercedes Benz Star Technician (2 times) 44 years foreign automotive repair 27 Years M.B. Shop foreman (dealer) MB technical information Specialist (15 years) 190E 2.3 16V ITS SCCA race car (sold) 1986 190E 2.3 16V 2.5 (sold) Retired Moderator |
#4
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Kind of what I thought. Thanks, MB Doc.
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"It's not about how fast you can go, but how well you can go fast." Bob in Richmond '97 S320 (LWB), Ruby Red Metallic, 73k miles '97 S420V, Smoke Silver Metallic, 155k miles |
#5
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Well, I am new to this forum and my goal is not to challenge, but...
brake fluid sucks up moisture like there is no tomorrow, right? If this is true, I don't believe it could be kept for two years with a broken seal. Air and moisture can seep through the threads and feed the fluid with moisture. I don't think a couple of weeks would do harm but I think it is worth the purchase of new fluid if it has been sitting for some time. |
#6
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Two years sounds about right to me (chemist) with some variation allowed for storage conditions. Two years in my MB is about the maximum I allow also. Must work, my calipers have only had pads replaced for the last 25 years.
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Charles 1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html |
#7
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Benz recommends changing due to hygro absorbtion every two years b/c the fluid in the reservoirs is open to ambient air humidity conditions thru the cap venting system.
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A Dalton |
#8
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That's my point too. Surly the can with the broken seal but a tight lid can be no worse than the reservoir.
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Charles 1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/showthread.php?t=296386 |
#9
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Getting more involved and interesting, if...
1. MB suggests fluid replacement every two years because of ambient air humidity conditions thru the cap venting system, and 2. a tight lid can be no worse than the previous then the fluid put in the car is already two years old and would need to be replaced by MB standards, if put into the car it would come out four years old, right? |
#10
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When in doubt, throw it out.
When it comes to a life safety feature like brakes, or critical operational pieces like transmissions and cooling system, why not always use new and fresh? |
#11
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<
Who said it should be put in the car?? What was said is it could have a 2 year shelf life..just like the reservoir has. One would not add a 2 year shelf life fluid to the res. b/c it has already expired it's 2 year shelf life. The main point is the question was asked about a can that had been opened and recapped a week ago...that fluid would not have hygroscopic contamination to the point of non/use. I think we are all in agreement , one way or another. I purposely buy brake fluid in the plastic 1 quart containers so that after I use some , I squezze the bottle until the fluid rises and then recap it. This gets most of the air out of the container and as the container attemps to reform to it's original shape [plastic memory], it creates a partial vacuum inside that helps the cap reseal well and limits the amount of air contained..........
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A Dalton Last edited by Arthur Dalton; 05-29-2008 at 11:54 PM. |
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