Thoughts on Replacing Brake Fluid every 24K per Maint Schedule??

cybercruiser

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2015 CX-5 Touring 2.5L FWD
In the past I've ran cars well over 200,000 miles and don't replace the brake fluid, unless there's an apparent reason.

My CX-5 Maint Schedule recommends replacing brake fluid every 24K, that seems a bit too often.

I know these new cars use brakes for much more than earlier models, so, maybe it is that important to keep fresher fluid??

Thoughts??

2015 CX-5 Touring FWD(early model, not 2015-1/2)
 
Well, it certainly will not hurt anything.

I did mine at 48 months and it was clean in both cars.
 
Well, it certainly will not hurt anything.

I did mine at 48 months and it was clean in both cars.

Many people misunderstand or are simply unaware of why there is a need to regularly change brake fluid. You wont necessarily be able to see contaminants such as moisture.

I am sure that Anchorman, our resident expert on all matters “braking” will chime in shortly, but in the meantime, here is an extract from AA1car explaining why:

“Many experts have long recommend changing the brake fluid every year or two for preventative maintenance. Their rationale is based on the fact that glycol-based brake fluid starts to absorb moisture from the moment it is put in the system. The fluid attracts moisture through microscopic pores in rubber hoses, past seals and exposure to the air. The problem is obviously worse in wet climates where humidity is high.

After only a year of service, the brake fluid in the average vehicle may contain as much as two percent water. After 18 months, the level of contamination can be as high as three percent. And after several years of service, it is not unusual to find brake fluid that contains as much as seven to eight percent water.

An NHTSA survey found that the brake fluid in 20% of 1,720 vehicles sampled contained 5% or more water!

As the concentration of moisture increases, it causes a sharp drop in the fluid's boiling temperature. Brand new DOT 3 brake fluid must have a dry (no moisture) boiling point of at least 401 degrees F, and a wet (moisture-saturated) boiling point of no less than 284 degrees. Most new DOT 3 fluids exceed these requirements and have a dry boiling point that ranges from 460 degrees up to over 500 degrees.

Only one percent water in the fluid can lower the boiling point of a typical DOT 3 fluid to 369 degrees. Two percent water can push the boiling point down to around 320 degrees, and three percent will take it all the way down to 293 degrees, which is getting dangerously close to the minimum DOT and OEM requirements.

DOT 4 fluid, which has a higher minimum boiling temperature requirement (446 degrees F dry and 311 degrees wet) soaks up moisture at a slower rate but suffers an even sharper drop in boiling temperature as moisture accumulates. Three percent water will lower the boiling point as much as 50%!

Considering the fact that today's front-wheel drive brake systems with semi-metallic linings run significantly hotter than their rear-wheel drive counterparts, high brake temperatures require fluid that can take the heat. But as we said earlier, the brake fluid in many of today's vehicles cannot because it is old and full of moisture.

Water contamination increases the danger of brake failure because vapor pockets can form if the fluid gets too hot. Vapor displaces fluid and is compressible, so when the brakes are applied the pedal may go all the way to the floor without applying the brakes!

In addition to the safety issue, water-laden brake fluid promotes corrosion and pitting in caliper pistons and bores, wheel cylinders, master cylinders, steel brake lines and ABS modulators.”
 
My 2014 CX5 maintenance schedule shows only to INSPECT the fluid at intervals up to 48 months which is four years and there is NO BF flush listed. I will do a BF flush when I change pads at about 75,000 miles or 6 years. Ed
 
In addition rtf Moonlighter’s comments, the big danger in not changing the fluid is the risk of damage by the moisture to the ABS/VSC components. Mine gets new DOT3 every 2 years and I strongly recommend everyone does the same regardless of mileage.
 
In addition rtf Moonlighter’s comments, the big danger in not changing the fluid is the risk of damage by the moisture to the ABS/VSC components. Mine gets new DOT3 every 2 years and I strongly recommend everyone does the same regardless of mileage.

Yep, thats been the recommended practice for many years, and I’ve always done that regardless of which make of vehicle that I have had.

Especially since I do a reasonable amount of towing a 1.2 tonne boat, I want to be sure those brakes will do their job, no questions asked.
 
My 2014 CX5 maintenance schedule shows only to INSPECT the fluid at intervals up to 48 months which is four years and there is NO BF flush listed. I will do a BF flush when I change pads at about 75,000 miles or 6 years. Ed

That is longer than I would recommend Ed, especially in humid FL. Brake fluid is so cheap to purchase, and by the time 2 yrs have passed in a humid environment, it is due for changing. 48 months would be the longest I would ever consider waiting. The current discount parts price on just an ABS pump ($506) and Master cylinder ($249) for your 2014 CX-5 is $750.

For those that are curious about the status of their fluid, DIP-STRIPS are available for testing your fluid.
 
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I've always read that brake fluid is hydrophilic so I change it every two years. It's a lot cheaper than replacing brake components.
 
It says R in ours (Europe). There is also a note “12” to say change annually under heavy duty or mountainous conditions.
 
cybercruser: Show us were your manual has a "recommended" brake fluid change every 24,000miles I just checked the Mazda CX5 maintenance schedule for the severe service and the recommendation is to check the brake fluid at selected intervals to 96,000 miles. There is NO recommended flushes or fluid exchanges listed. Ed
 
I suspect one may be required to change more often if I lived in Europe or ? and drove in mountainous regions. Ed
 
It says R in ours (Europe). There is also a note 12 to say change annually under heavy duty or mountainous conditions.

Europeans are kinda' bonkers about brake fluid flushes (IMO). Seems like every time I turn around it's time for a flush on my wife's Z4 BMW. And yet you guys don't bother to rotate tires. Go figure!(shrug)
 
Who is to say that the “I” does not mean that the fluid is to be tested using one of those strips? And replaced if the results indicate that its condition is not suitable?

The simple assumption might be that “I” just means check the level. But that is just an assumption.....
 
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I will admit this isn't something I have been up on. In several previous vehicles had it changed at 5 years. My G is still stock at 10 years.... not a good thing but never detected any impaired braking. Perhaps the braking is so good that deterioration is not as easily noticed. I still need to address this. My service history on my GX indicates Lexus changed it at 30K miles. I can tell by color this likely did occur. Not sure about Mazda but some manufacturers like Nissan and maybe Toyota there is special procedure for draining out the brake lines or you could cause issues with the ABS actuators if not damage. That is what my my G's FSM says anyway. The Nissan Consult system is used for that service.
 
Color is a LAGGING indicator. By the time the old brake fluid allows the system to rust/corrode and you start seeing any "color" to the clear/amber fluid, it is too late to prevent damage.

Enough moisture absorbs into your brake fluid in just 3 years to reduce the boiling point of the fluid by almost half. This same 3 year old fluid will "look fine", but if you actually test it, it will show you the actual status.

A NEW bottle of brake fluid that has been opened, resealed and put on a shelf, has a recommended shelf life of 12 months. *As per CASTROL.

amsoil_bf3_water_contamination_and_brake_fluid.jpg


There is a digital tester available for $10-$25 depending on brand.
Brake-Fluid-Tester.jpg


Here is the link to the cheap version on amazon. Can also find in the autoparts stores, ebay, Walmart, etc..
https://www.amazon.com/dp/ (commissions earned)
 
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Europeans are kinda' bonkers about brake fluid flushes (IMO). Seems like every time I turn around it's time for a flush on my wife's Z4 BMW. And yet you guys don't bother to rotate tires. Go figure!(shrug)

We didnt make the rules, Mazda did!
 
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