[Grease23]

This was theoretical for me before I purchased a 1960's British car in Redding, CA and drove it down to Los Angeles. Roughly 600 miles. Near home, it started to pull to the right, no matter what I did. That got worse and worse. The FR caliper was stuck because it was internally rusty. (On disassembly I found it was filled with chunks of rust that looked like coffee grounds.) As I exited for home, the fluid in that caliper got hot enough to boil the moisture it contained. The pedal went almost all the way to the floor and braking was, at best, slight. Downshifting + handbrake + getting off the road.

There was a widely reported bus accident years ago caused by boiling fluid. An old IH bus had a single master and the fluid boiled and it lost its brakes coming down the Whitney Portal road.

Even if the fluid boils in only one half of a dual system, the driver often interprets the loss of braking and very low pedal height to total brake failure when it really isn't quite that.

[Miodek233]

Thank you for the info, very useful post.

[RockCrusher]

Originally Posted by BWBike

Add me to the list of owners who don’t change their brake fluid.

I never had a BMW before, but my two current cars are over 10 years old and the original brake fluid. The braking performance has not diminished.

With that stated, I’m thinking I will change the brake fluid after hearing these comments.

Unless you track the car and get the brakes good and hot you probably won't really notice any issues from old brake fluid.

However, I can assure you that brake fluid at just 2.5 years of age has experienced degradation.

With one car -- a 2002 Boxster -- this manifested itself by negatively affecting clutch behavior -- the clutch hydraulic system shared fluid with the brake hydraulic system -- which a brake fluid service addressed.

Then with 2 other vehicles (a 2018 MINI JCW and a 2020 M-B Metris van) brake fluid just 2 years in service required a change to address issues. With the JCW fresh brake fluid cured an overly sensitive stability control system. With the Metris fresh brake fluid eliminated erratic braking action under normal driving.

[jamesinaz]

Originally Posted by KevinC

Speaking of the wheel alignment suggestion - WHY? Did they put it on the rack and verify it's out of spec? Highly unlikely. Uneven tire wear? If so they should have pointed it out to you. Or is the old "well you need an alignment because you haven't had one" or some such BS? Which dealership was this btw - BMW North Scottsdale? It's bad enough when a dealership (or indy shop for that matter) recommends stuff that isn't necessary, but when they do that they want to absolutely rob you for the work - inexcusable and should be called out for it.

I do not know if they did anything legitimate to determine the need for a 4 wheel alignment. I had the car in for an oil change and nothing more for a fixed price. The service rep came out while I was waiting and said the tech noticed it needed brake flush and change and 4 wheel alignment for a total of $1100. And you have the correct dealership.

[JABCAT]

Originally Posted by jamesinaz

Thanks. I am baffled that this is a new thing? Or did we just not know before?

Changing brake fluid (along with most other fluids) has always been a part of regular maintenance. It's also an included service on my '22 & '23 M vehicles. Dealership does it free of charge at around 25k mi.

I recommend downloading your vehicle-specific maintenance manual from the BMW website (or in your app).

[Grease23]

I might add that if you are not DIY then you need to be specific. "Bleed my brakes" is what a lot of people say or ask for. To many mechanics, that means cracking open the bleed screw for a few pumps to get out air bubbles, if any.

What you really need to do is crack open the bleeder while fresh fluid is added. Pumped through (or sucked out, depending on your setup) until the fresh fluid (lighter yellow color) fluid comes out with no more of the tea colored old fluid. If you're watching at the bleeder through a clear vinyl tube the change is pretty obvious, even after just two years.

If you pick your car up and the fluid in the reservoir isn't clean and yellow-ish, then something other than a "change" of fluid was performed.

[tturedraider]

So no one is denying that changing brake fluid is a necessary, routine maintenance item, but regardless, the fact of the matter is, “normal” car manufacturers and dealerships never talk about it or bring it up. That’s a fact. I’m not a serious mechanic. Only a shade tree mechanic. But, I am a fairly technical gearhead and a car enthusiast since before I could drive. I’ve owned Buick, Oldsmobile, MG, Mazda, Nissan, and Infiniti before I got my first BMW and joined the BMW enthusiast crowd at the age of 44. My parents owned Fords, Chevys, Pontiacs, Mercurys, and Buicks. I had never once heard anyone talk about changing brake fluid in all those years, including my gearhead dad or his gearhead buddy who worked on cars with him. My impression is this is a pretty European car owner topic. I think I can pretty safely guarantee Toyota Camry and Honda Accord owners who are doing well to get their oil changed on a regular basis are not ever thinking about having their brake fluid changed, much less doing it every two or three years.

[freakystyly]

Brake fluid is brake fluid, Ferrari or FIAT.

The average owner doesn't have that on their mind, agreed. It should be part of the mechanic's vehicle check depending on the quality of the shop of course. Some places do the inspection for free, some charge extra. A lot of customers view it as an upsell even though it's regular maintenance.

A co worker was shocked his dealer recommended changing his F150s spark plugs at 150kkms. A lot of people kick the maintenance can down the road.

[jamesinaz]

OK last question. Since the concern is water in the fluid does living in a desert make a difference? Here in the Phoenix area humidity levels are a tad lower than most parts of the world.

[Grease23]

I'm sure fluid picks up more moisture in Portland than in Phoenix.

[JABCAT]

All vehicles come with owner's manuals and maintenance schedules. Read them. It's not on the dealership to tell you what service is required. All four of my children had to read the owner's manual of their respective vehicles before they were allowed to drive them. They had to learn to change a tire, check & change the oil, check other fluids, know the general maintenance intervals & where to find them in said manuals. Especially my daughters so I never have to worry about one of them calling me saying "the mechanic says I need to change my headlight fluid".

I see this all the time on Corvette Forum as well (because I own one). Check out my "mint" 2005 Corvette - still on original tires and regular oil changes, only 7k miles. "Have you changed the coolant" "no, it only has 7k mi". "Have you changed the brake fluid, clutch fluid, rear diff fluid...?" "No it only has 7k mi".

I never understood people paying a lot of money for something & not knowing how it works or how to maintain it properly. Even supposed "gear heads".

[eluded]

You can buy a moisture brake fluid test device on Amazon for pretty cheap. Then you will know the water content.

Originally Posted by jamesinaz

OK last question. Since the concern is water in the fluid does living in a desert make a difference? Here in the Phoenix area humidity levels are a tad lower than most parts of the world.

[pbonsalb]

Originally Posted by JABCAT

All vehicles come with owner's manuals and maintenance schedules. Read them. It's not on the dealership to tell you what service is required. All four of my children had to read the owner's manual of their respective vehicles before they were allowed to drive them. They had to learn to change a tire, check & change the oil, check other fluids, know the general maintenance intervals & where to find them in said manuals. Especially my daughters so I never have to worry about one of them calling me saying "the mechanic says I need to change my headlight fluid".

I see this all the time on Corvette Forum as well (because I own one). Check out my "mint" 2005 Corvette - still on original tires and regular oil changes, only 7k miles. "Have you changed the coolant" "no, it only has 7k mi". "Have you changed the brake fluid, clutch fluid, rear diff fluid...?" "No it only has 7k mi".

I never understood people paying a lot of money for something & not knowing how it works or how to maintain it properly. Even supposed "gear heads".

We do not all have climate controlled garages in which to store our rarely driven car collections. I agree service needs are reduced in such cases. Even in other cases, I would reduce servicing. But for those of us whose cars live in the real world where they are subjected to repeated hot cold cycling due to temperature changes whether driven or not, there can be condensation that adds moisture. A moisture meter to check the fluid or using a less hygroscopic fluid could be a good idea.

[POBEP]

please read the manual.

(you) owned cars since 1970s and just discovered that brake fluid needs periodic replacement?
yet, clearly remember that (modern) engine oil still needs to be changed every 3000mi?

please read the manual.

* DOT4 absorbs moisture faster than DOT3. hence more frequent changes.
* I had a 15y Accord that never saw a break fluid change from the first owner - rear cylinders/pistons had to be replaced due to rust
* The 2y interval could be a bit conservative in dryer climates
* I use moisture tester - it shows in CA (coastal & mountain areas) 4yr is about the right time

please read the manual.

At the end, it is just a 1h DIY job with $20 for 1l of DOT4 (low viscosity) bottle.

[JABCAT]

Originally Posted by pbonsalb

We do not all have climate controlled garages in which to store our rarely driven car collections. I agree service needs are reduced in such cases. Even in other cases, I would reduce servicing. But for those of us whose cars live in the real world where they are subjected to repeated hot cold cycling due to temperature changes whether driven or not, there can be condensation that adds moisture. A moisture meter to check the fluid or using a less hygroscopic fluid could be a good idea.

I'm not sure what this has to do with anything I said that you quoted?

[TrueRace]

Rule of thumb and good maintenance requires brake fluid to be replaced every 2 years(it is resettable as such in inspection menu). I do mine on my X5 like that. My friends more in love with better maintenance, they replaced it through bleeding every 1 year. Based on my experience I recommend every 2 year and no longer than 3 years to avoid contamination in the system which can then affect the seals.

[XutvJet]

Unless you are tracking a car, the recommended brake fluid changes in German cars is extreme.

I have a brake fluid tester and I have yet to find a fluid that doesn't go out of spec (i.e., 2%+ moisture) until around 4 to 5 years. My M235's 4 y/o fluid still tested at just under 2% when I sold it. My daughter's 2015 Outback, which we've owned since new, didn't exceed 2% until year 7.

I've been driving since 1989 and have done all my maintenance for as long as I can remember. Not until I got my new 2016 M235 back in late 2015 did I bother with brake fluid changes.

I've NEVER had a brake related issue in the 15+ cars I've owned between me, my wife, and kids. No fade, no degraded/fail brake lines, no ABS issues, etc.

I'm not saying don't routinely change your brake fluid, but for most cars, every 2 years is unnecessary and is just a money grab and another way to get a customer into a shop, put some fright into them because they are "brakes", and upsell on other services. There is nothing special about the internals and operation of a German car braking system compared to any other make.

[BlkGS]

Originally Posted by XutvJet

Unless you are tracking a car, the recommended brake fluid changes in German cars is extreme.

I have a brake fluid tester and I have yet to find a fluid that doesn't go out of spec (i.e., 2%+ moisture) until around 4 to 5 years. My M235's 4 y/o fluid still tested at just under 2% when I sold it. My daughter's 2015 Outback, which we've owned since new, didn't exceed 2% until year 7.

I've been driving since 1989 and have done all my maintenance for as long as I can remember. Not until I got my new 2016 M235 back in late 2015 did I bother with brake fluid changes.

I've NEVER had a brake related issue in the 15+ cars I've owned between me, my wife, and kids. No fade, no degraded/fail brake lines, no ABS issues, etc.

I'm not saying don't routinely change your brake fluid, but for most cars, every 2 years is unnecessary and is just a money grab and another way to get a customer into a shop, put some fright into them because they are "brakes", and upsell on other services. There is nothing special about the internals and operation of a German car braking system compared to any other make.

Overall, I agree. I do mine with brake jobs. It's a convenient time to get new fluids in.

That said, it is something I do when I buy a used car that's more than a couple years old. I like to baseline my upkeep.

[Redd]

I find it amusing that there are people who are religious about oil changes but think it's OK not to change other fluids including brake, trans and coolant. All fluids will degrade over time - some faster than others - and all of them need to be changed.

[shawnhayes]

Old old cars used DOT 2 brake fluid. This was a castor oil/alcohol fluid. It would generally last a LONG LONG time. This is why a lot of old cars suggest "testing" the brake fluid instead of replacing it (I've checked - 1960 chevrolet had a 10,000 mild brake fluid "check")

Later DOT 3 fluids were hygroscopic. In general, SOME part of the brake system leaked/failed/required replacement, and as a result, a sort of "bleed"/"replacement" on a pretty regular interval.

DOT 4 is even MORE hygroscopic, and flushes/changes are needed to avoid internal rusting of the brake components.

The problem NOW is two-fold. More people are keeping cars MUCH longer. AND, the seals on brake calipers are MUCH more durable. The result? Older cars with older fluid, and with DOT 4 it gets saturated with water. Even FORD added a brake fluid "change" interval to all its cars in 2020. So, if you're NOT going to do a brake fluid change interval, at least get a moisture detector.

There WAS an effort to try to make this problem go away, especially for classic cars. It was DOT 5 fluids. These are silicone based, and don't absorb water much. The prolem? They compress more and don't brake as well. It's just a thing. Some people use them on that old Nash they restored and drive only on/off the trailer for the car show. Not recommended for road cars.

The other historical issue? The VAST majority of cars in the early DOT 3 years was that cars generally just didn't last that long. You'd sometimes get a grill badge if you lasted more than 100,000 miles. There are now cars with well over a million, and even some multimillion mile lives. This problem is now much more recognized and dealt with.

Shawn

[TrueRace]

All I’m saying in “Next Service” or “Services” BMW menu is stipulated that brake fluid has to be replaced every 2 years. On my X5 which uses DOT 4 LV, low viscosity break fluid. That if you don’t want to run it with faults or warnings. It has been set by BMW at 2 years intervals. You have to reset it as such.

[XutvJet]

Originally Posted by Redd

I find it amusing that there are people who are religious about oil changes but think it's OK not to change other fluids including brake, trans and coolant. All fluids will degrade over time - some faster than others - and all of them need to be changed.

I don't think any of us are saying that. Most of us understand that vehicle fluids have a life expectancy. It also pays to test fluids and there are plenty of cheap products on the market that you can use to test brake fluid, coolant, and such. It is a dealer/shop's vested interest to sell you on all sorts of maintenance services as they make them a ton of money.

BMW's 2 year brake fluid service interval is largely based on folks driving high speeds on the autobahn where high MPH stops can result in potential brake fade issues. Us in the US typically are driving well below 50mph and on the highways, 80mph and usually more like 65mph in most places on average. Brake fade isn't much of an issue during a single panic stop from 80mph to 30mph vs one at 120mph to 40mph. The German makes are just bonkers about their brake fluid changes but if you go to an Asian or domestic shop, they hardly ever recommend a brake fluid change unless it's been years, the car really old, and/or the fluid in the reservoir brownish. Those cars use DOT 3 or 4.

Lastly, I've tested 4 y/o brake fluid on my M235 at the reservoir and at the caliper. Hardly any measurable difference and within 0.5% of a percent, thus, so much for that argument and it really opened my eyes to how needless a 2 year fluid change is on a street driven only car. Now if I was tracking any of my cars on occasion, I'd be changing the fluid probably every year for obvious reasons.