Three Year Brake Fluid Changeout

[ThomF]

My vehicle is coming up on the three year mark. It's been essentially problem-free, with little maintenance required. But I see that Ford specifies that the brake fluid be changed at the three year mark. Does anyone know why? Is it something to do with the regenerative braking system?

I have never had to change-out brake fluid on a vehicle in the past, even over a ten year period. And my previous vehicle was a hybrid, which used regenerative braking and I never experienced the issue.

Are others following this maintenance requirement? Thoughts?

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[Sikkun]

Manufactures of vehicles say 2-3 years 20-30k miles give or take.

Some people never do it without problems. Some people never do it with problems.

 

[dalola]

Brake fluid is formulated to absorb water (for safety reasons), so it will become contaminated over time. It's a simple/cheap process if you have a vacuum bleeder. I like to do all my vehicles every 2 years, but that's just me. ?

 

[jsteach]

Brake fluid is hygroscopic, meaning it readily absorbs water from the air, lowering its boiling point and impacting braking efficiency.
Regular fluid changes ensure optimal braking performance by replacing contaminated fluid with fresh, dry fluid, preventing issues like brake fade, corrosion, and potential failure in extreme braking conditions.

 

[Mach-Lee]

My vehicle is coming up on the three year mark. It's been essentially problem-free, with little maintenance required. But I see that Ford specifies that the brake fluid be changed at the three year mark. Does anyone know why? Is it something to do with the regenerative braking system?

I have never had to change-out brake fluid on a vehicle in the past, even over a ten year period. And my previous vehicle was a hybrid, which used regenerative braking and I never experienced the issue.

Are others following this maintenance requirement? Thoughts?

Brake fluid is hygroscopic and absorbs water from the air, which degrades it. Fluid should be checked for moisture annually starting at the 3-year mark and replaced when the moisture level is too high. In humid environments like Florida, the fluid may need to be changed at 3 years, but in drier or less humid environments, it might be able to go for up to 5 years between changes.

 

[aclosedmind]

Factory brake lines are technically porous as well. It will absorb some water even if you rarely use the friction brakes

 

[Murse-In-Airy]

Brake fluid is formulated to absorb water (for safety reasons), so it will become contaminated over time. It's a simple/cheap process if you have a vacuum bleeder. I like to do all my vehicles every 2 years, but that's just me. ?

Have you done it with a vacuum bleeder on this car? Because the service manual literally says, “attach to FDRS and follow prompts.” So I’m not sure if a vacuum bleeder would work to pull the fluid through or if there is some kind of valve between the master cylinder and the caliper.

 

[E. Shore Farmer]

I have always been skeptical of brake fluid replacements, Whether good practice or not, with one exception, in over 50 years I have never done a fluid replacement, and never had a problem I did have a rust incident with rusty brake lines once, but that was a 2007 Chevy pickup, and those lines apparently rusted from the outside. (Nice work, General Motors).

 

[Scooby24]

My vehicle is coming up on the three year mark. It's been essentially problem-free, with little maintenance required. But I see that Ford specifies that the brake fluid be changed at the three year mark. Does anyone know why? Is it something to do with the regenerative braking system?

I have never had to change-out brake fluid on a vehicle in the past, even over a ten year period. And my previous vehicle was a hybrid, which used regenerative braking and I never experienced the issue.

Are others following this maintenance requirement? Thoughts?

Brake fluid has a not dissimilar interval for most cars, but I'd argue that in cars like ours where we virtually never get our brake fluid up to any sort of moderate temps, the typical water absorption problems associated with fluid may be exacerbated.

You're not worried about the fluid in your daily driving scenarios...you wouldn't/won't notice a difference. It's that rare emergency braking scenario you're changing it out for where you cannot take the chance that the fluid would boil at a lower temp than expected.

BUT...with our regenerative braking system which makes it so even on long sweeping downhill drives you're almost never needing to use the brakes...I dunno.

I used to be an avid autocrosser and HPDE driver who is OCD about brake fluid...but I'm at 3 years and not in any rush to swap mine out so I guess take that for what it's worth.

 

[E. Shore Farmer]

Being the old codger Boomer I am, the (American) cars of my youth never had a maintenance interval for brake fluid. Now, those American cars as I'm sure you remember, had sealed brake systems (as opposed to the "vented" systems in use today). The old systems had snapped-down metal covers on metal fluid reservoirs and used a rubber diaphragm under the cap to seal the air gap as the pads thinned and the caliper/slave cylinder created a void in the system fluid level. Also, American cars used DOT3 fluid, which has a very low propensity to absorb water vapor.

My belief is modern vented brake systems primarily absorb water via the vent built into the reservoir cap. The system has to be vented so as to prevent a vacuum lock as the pads thin and the fluid level drops. As the brake fluid absorbs water more readily than a sealed system, the fluid requires period replacement. It wasn't until I bought my first BMW in the 1980's did I own a car with a DOT4 vented brake system, which required annual brake fluid flushing (hence BMW's early reputation for high cost of ownership...).

Ike,
Thanks. I was basing my comments mostly on the junkers which I drove early on. Back then, disc brakes were only on airplanes, and in 1963, on the Avanti. Guess I need to join up with the 21st century.
Ben

 

[superdave80]

I've had several vehicles over the years, with a few reaching 200k+ miles and over a decade of ownership. I have never replaced the brake fluid on any of them.

Just because, I just looked up my old 99 Mustang and 01 Murano manuals, and it does not call out an interval for brake fluid replacement. Ever. They do call for inspecting the brake system, so it's possible within that procedure there is a test of the fluid to see IF the fluid has gone bad.

In my opinion, three years is way too aggressive a replacement schedule, and has been recently added to the maintenance schedule by manufacturers to get more money for dealerships. And every time you open up and replace all the fluid you introduce the chance of some contaminants.

 

[Teslaeata]

Correct advice is always follow maker’s specifications.

It’s there for a reason.

Changing brake fluid is a preventive measure worth taking - a good insurance policy.

Not only is there a risk of vapour-locking and so complete brake failure, there is a risk of the hidden effects of moisture and other wear debris within the hydraulic system corroding, deteriorating and wearing parts from within the consequence of which we’d all moan about when they let us down and we would not know that the brake fluid was the reason.

 

[dalola]

I had to Google the "for safety reasons" comment. I've been working on cars for the better part of 4 decades and have been flushing brake systems for nearly as long. I've never read anywhere in any technical documentation or the numerous repair manuals I've collected over the years that stated brake fluid is purposefully formulated to absorb water (and especially for "safety reasons"). My understanding has always been, brake fluid chemicals absorb water over time and require changing because the absorbed water (a) can lead to internal corrosion of the brake system, and (b) can create reduced braking effectiveness at high fluid temperatures if the air trapped in the fluid boils (turns to gas vapor) and causes a "spongey pedal".

Too my astonishment a Google search did bring up the idea DOT 3, DOT 4, and DOT 5.1 are formulated to suspend water in the fluid to prevent "pooling" in the system and reduce the chance of corrosion forming in the brake components. I found the "pooling" phenomenon is discussed in relationship to DOT5 fluid, which is silicone based and doesn't absorb water, which makes sense. But DOT 3/4/5.1 being purposefully formulated to absorb water "for safety reasons" (i.e. corrosion prevention via "pooling") I'm not buying that argument. The internet is full of misinformation.

I don't know where Timbucktoo is, but if you live in a cold weather state, it should be rather obvious why you don't want water pooling or separating in your hydraulic brake system. This is why DOT5 is also not recommended for on-road vehicles, especially in cold weather states. It's not an argument, it's fact. ?

 

[dalola]

Have you done it with a vacuum bleeder on this car? Because the service manual literally says, “attach to FDRS and follow prompts.” So I’m not sure if a vacuum bleeder would work to pull the fluid through or if there is some kind of valve between the master cylinder and the caliper.

Not yet, but I'm certain it will work fine. Typically, to get a more thorough flush, OEM's want you to use their system, which cycles the ABS modulator, to release fluid from the solenoids. It's similar to an automatic transmission, where you just gravity drain, and refill, vs. system flush including the TC. Of course, that's better, but not 100% necessary, especially if you change ahead of schedule. I'll let you know in 2 years if it works! ?

 

[VindictivePantz]

It was $168 for the dealer to perform the work for me. and did not take much time.

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