Brake fluid ageing?

Status
Not open for further replies.
Joined
Jun 14, 2011
Messages
113
Location
Denmark, Europe
Hi,

I have some brake fluid questions and need some "everyday" answers :)

1. How often is it necessary to change the brake fluid? I know the maintenance manual says something - but I truly feel that most cars rarely have their brake fluids changed and basically nothing happens. I know the brake fluid might boil when it gets really hot like in the mountains - but has anyone heard of such cases?

2. I have a bottle of DOT4 brake fluid on my shelf. It was opened 1 or 2 years ago and the lid was closed again of course. From a visual point of view the fluid looks just fine. Can it still be used? I mean when the brake fluid is in the reservoir of the car you could compare it as an open bottle ... and I think most cars run on the same brake fluid for YEARS without any complications ... so my conclusion is that I can use it. What is your opinion?

Lucas
 
According to some sources brake fluid should be changed every 2 years.

If you're going to go through the effort of changing the fluid I would not use an opened bottle that is one to two years old.

Brake fluid takes on moisture. Once you open the container and drain fluid out of the container that fluid is replaced with air containing moisture. I'd pitch it and use fresh new fluid.
 
I change it every two years on street driven cars and every six months on track rats. The moisture in the brake fluid CAN lower the boiling point to a dangerous level- not to mention that it may cause damage to some components of the ABS system.
 
Why guess when you can know?

About 10 months ago I bought a 12 year old, 50K mileage garaged cream puff from a retired Army Officer. He dutifully changed the oil every 3K (waste), and even used dealer touch up paint on a few bumper scratches, but he put in the wrong antifreeze and I had no idea if he EVER changed the brake fluid...

I took the car to a GM dealer and a Mr. Goodwrench, who said "Yes, the fluid looks dirty, I'd change it." I said, (being the arrogant snob who does UOA), "OK, but I want something more than your opinion, I want empirical evidence." They had none.

Here is empirical evidence for under $10: http://www.amazon.com/Phoenix-Systems-30...luid+test+strip

Incidentally, I DID end up changing my brake fluid, but this last weekend I tested the fluid in my 2004 Impala, which had a brake flush in 2009; the fluid tests OK. I also use small plastic syringes to pull small samples of brake fluid, PS fluid, antifreeze, etc., so I can hold them up in the sunlight and get a good LOOK at them. No, I don't go by some grease jockey's opinion, and you don't need to either. There are also antifreeze ph test strips available: http://www.ebay.com/itm/AquaChek-Cool-Trak-311519-Coolant-pH-Boilpoint-Freezepoint-Test-Strips-50-Pack/351640965907?_trksid=p2045573.c100034.m2102&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36501%26meid%3D65d5a3309af348e3b17d8006146c0545%26pid%3D100034%26rk%3D1%26rkt%3D8%26sd%3D311550968232

BTW, I would not use the old opened fluid you have. There is a reason they are sealed from the factory; yes, moisture is harmful.
 
Originally Posted By: Ihatetochangeoil
Why guess when you can know?

About 10 months ago I bought a 12 year old, 50K mileage garaged cream puff from a retired Army Officer. He dutifully changed the oil every 3K (waste), and even used dealer touch up paint on a few bumper scratches, but he put in the wrong antifreeze and I had no idea if he EVER changed the brake fluid...

I took the car to a GM dealer and a Mr. Goodwrench, who said "Yes, the fluid looks dirty, I'd change it." I said, (being the arrogant snob who does UOA), "OK, but I want something more than your opinion, I want empirical evidence." They had none.

Here is empirical evidence for under $10: http://www.amazon.com/Phoenix-Systems-30...luid+test+strip

Incidentally, I DID end up changing my brake fluid, but this last weekend I tested the fluid in my 2004 Impala, which had a brake flush in 2009; the fluid tests OK. I also use small plastic syringes to pull small samples of brake fluid, PS fluid, antifreeze, etc., so I can hold them up in the sunlight and get a good LOOK at them. No, I don't go by some grease jockey's opinion, and you don't need to either. There are also antifreeze ph test strips available: http://www.ebay.com/itm/AquaChek-Cool-Trak-311519-Coolant-pH-Boilpoint-Freezepoint-Test-Strips-50-Pack/351640965907?_trksid=p2045573.c100034.m2102&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36501%26meid%3D65d5a3309af348e3b17d8006146c0545%26pid%3D100034%26rk%3D1%26rkt%3D8%26sd%3D311550968232

BTW, I would not use the old opened fluid you have. There is a reason they are sealed from the factory; yes, moisture is harmful.


Assuming someone can change their brake fluid themselves it would be cheaper to just do a quick bleed vs using those strips. Also, those strips may tell you the condition of the fluid in the reservoir but how about the fluid that is in the caliper?
 
Originally Posted By: LucasDK
Hi,

I have some brake fluid questions and need some "everyday" answers :)

1. How often is it necessary to change the brake fluid? I know the maintenance manual says something - but I truly feel that most cars rarely have their brake fluids changed and basically nothing happens. I know the brake fluid might boil when it gets really hot like in the mountains - but has anyone heard of such cases?

2. I have a bottle of DOT4 brake fluid on my shelf. It was opened 1 or 2 years ago and the lid was closed again of course. From a visual point of view the fluid looks just fine. Can it still be used? I mean when the brake fluid is in the reservoir of the car you could compare it as an open bottle ... and I think most cars run on the same brake fluid for YEARS without any complications ... so my conclusion is that I can use it. What is your opinion?

Lucas



Most OEM recommendations I've seen call for a change every 2 years. The system is not 100% air-tight so moisture will slowly get in there.

Brake fluid absorbs water so an opened bottle (especially sitting for a year or more) has likely absorbed a decent amount of moisture from the air. Brake fluid is cheap enough that I would just buy a new bottle and recycle the old stuff. A visual inspection won't reveal much unless there is some crazy contamination in there.
 
Dot 4 at six years maybe seven years in my Volvo 240, and it was black looking in the quart jars. A slowly dying master cylinder probably sped up the process of the fluid going bad too. Installed new master cylinder, rotors, front disc pads, and new fluid. I think I might be able to get by changing the fluid every time it needs front disc brakes changed.
 
I change mine every 30k miles with a BG brake flush/fill. Im actually about due for one again soon.

And yes, bad things can happen if you don't change it regularly. I have a brake fluid level sensor that is corroded to ____ because the brake fluid wasn't changed frequently enough in an environment that has 100% humidity 11 months and 3 weeks out of the year.

Now my computer intermittently thinks that my braking system has had a catastrophic failure and throws on the red brake light and amber abs light simultaneously while sounding alarms that sound like I have a target lock on me from top gun...It would be an easy fix, if I didnt have to spend $700 on a new master cylinder assembly JUST because Dodge wont sell me the sensor alone.

Now granted, minor problem, braking system still operates just fine, but years of neglect can lead to some SERIOUSLY costly repairs to the ABS.

Food for thought.

As for the bottle of brake fluid: Ditch it. Brake fluid is hydrophillic. Adding old brake fluid is insult to injury.
 
Originally Posted By: dparm
Brake fluid absorbs water so an opened bottle (especially sitting for a year or more) has likely absorbed a decent amount of moisture from the air. Brake fluid is cheap enough that I would just buy a new bottle and recycle the old stuff.


The question is do the unopened Ate and Pentosin brake fluids in those METAL cans resist that moisture uptake better than the plastic bottles do, and stay in good condition for longer periods of time?
21.gif
 
I don't think there is a problem with plastic never mind metal. Master cylinder reservoirs are plastic and they are vented. How is a plastic bottle of fluid with the cap on only going to last 6 months when the fluid in a vented reservoir is good for two years.

I go off the color. If the fluid in the bottle is a light straw color I use it. If it's darkened I chuck it.
 
Originally Posted By: Nate1979
Originally Posted By: Ihatetochangeoil
Why guess when you can know?

About 10 months ago I bought a 12 year old, 50K mileage garaged cream puff from a retired Army Officer. He dutifully changed the oil every 3K (waste), and even used dealer touch up paint on a few bumper scratches, but he put in the wrong antifreeze and I had no idea if he EVER changed the brake fluid...

I took the car to a GM dealer and a Mr. Goodwrench, who said "Yes, the fluid looks dirty, I'd change it." I said, (being the arrogant snob who does UOA), "OK, but I want something more than your opinion, I want empirical evidence." They had none.

Here is empirical evidence for under $10: http://www.amazon.com/Phoenix-Systems-30...luid+test+strip

Incidentally, I DID end up changing my brake fluid, but this last weekend I tested the fluid in my 2004 Impala, which had a brake flush in 2009; the fluid tests OK. I also use small plastic syringes to pull small samples of brake fluid, PS fluid, antifreeze, etc., so I can hold them up in the sunlight and get a good LOOK at them. No, I don't go by some grease jockey's opinion, and you don't need to either. There are also antifreeze ph test strips available: http://www.ebay.com/itm/AquaChek-Cool-Trak-311519-Coolant-pH-Boilpoint-Freezepoint-Test-Strips-50-Pack/351640965907?_trksid=p2045573.c100034.m2102&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D36501%26meid%3D65d5a3309af348e3b17d8006146c0545%26pid%3D100034%26rk%3D1%26rkt%3D8%26sd%3D311550968232

BTW, I would not use the old opened fluid you have. There is a reason they are sealed from the factory; yes, moisture is harmful.


Assuming someone can change their brake fluid themselves it would be cheaper to just do a quick bleed vs using those strips. Also, those strips may tell you the condition of the fluid in the reservoir but how about the fluid that is in the caliper?


Time is money; I don't like wasting either. So what would be so harmful about loosening and bleeding the caliper farthest away from the master cylinder and testing THAT fluid? If it's OK, run it; regardless of age. And my 7 year old fluid is a nice straw color.
 
I do mine every 3 years,
I pay the stealership $90,
they supposedly have a tool that opens up the abs module to flush that too. it is worth the money,
Price an abs module and see how much it is.
 
for my older Toyotas,
I just suction out all the fluids from the reservoir and then start at the farthest end (pass rear and suction out till I see fresh fluid, repeat on each wheel
 
Yes, Brake fluid ages. Change it every two years!

I personnaly have expirienced brake problems and friends of mine also because of old brake fluid, and not in the mountains. In regular traffic!

If you open a Container, use it within a week or two and then discard it.

Brake fluid is "Hygroscopic". It collects moisture from the air. Old brake fluid mixed with this moisture (water) could cause rust inside the brake system. Calipers, ABS blocks, Brake lines are very expensive to replace.

Brake fluid and changing them is extremly cheap, especially compared to the issues old fluid can cause.

So, why seriosuly taking a risk just for saving a little bit of money every two years?
 
http://motorist.org/articles/auto-braking-systems

The Automotive Maintenance and Repair Association (AMRA) recommends to its members that (1) auto Brake fluid be tested for contamination at OEM recommended brake system inspection intervals, and (2) that a Brake fluid replacement service be performed, for most vehicles, when testing shows copper content exceeds 200 ppm. The AMRA Technical Committee reached these conclusions after extensive study of industry data, including a review of SAE Papers, US Government reports (NHTSA and NIST) and independent laboratory studies, among other resources. The data showed that this increased presence of copper contamination predetermines the rapid growth of iron contamination and corrosion which has shown to impede future brake system performance.

http://www.amazon.com/Phoenix-Systems-30...luid+test+strip
 
Originally Posted By: LucasDK
Hi,

I have some brake fluid questions and need some "everyday" answers :)

1. How often is it necessary to change the brake fluid? I know the maintenance manual says something - but I truly feel that most cars rarely have their brake fluids changed and basically nothing happens. I know the brake fluid might boil when it gets really hot like in the mountains - but has anyone heard of such cases?

2. I have a bottle of DOT4 brake fluid on my shelf. It was opened 1 or 2 years ago and the lid was closed again of course. From a visual point of view the fluid looks just fine. Can it still be used? I mean when the brake fluid is in the reservoir of the car you could compare it as an open bottle ... and I think most cars run on the same brake fluid for YEARS without any complications ... so my conclusion is that I can use it. What is your opinion?

Lucas


I have seen total hydraulic brake system failure happen suddenly and unexpectedly on vehicles that did not have proper maintenance and was directly attribute to the old fluid where it boiled.
The vehicles were otherwise "working fine".
The only saving grace was the manually operated Hand brake.

Brake fluid has a defined service life dependent upon the formulation.
Some formulations are stipulated to be changed at no longer than 1 year intervals.
The general rule is 2 years for normal vehicle maintenance schedules for good reason.
Brake fluid is extremely cheap in the grand scheme of things when it comes to vehicle maintenance.
In all practicality, very old Brake fluid is no good for anything other than to be used as weed killer.
The moisture that's continually drawn into the fluid through the rubber Brake lines and seals renders it a liability because it is designed to be Hygroscopic for overall system reliability reasons.
This design feature of the Brake fluid ultimately brings the demise of the fluid as a consequence.

IMO, fluid that's stored in the original container is most likely fine to use in hydraulic clutch systems designed for it when it gets old.
Possibly not so good in the Brake system as the safe life expectancy may be questionable.
 
Status
Not open for further replies.
Back
Top