Shark, the answer to your question is yes and no. Protecting the system components is a long term issue, but the more immediate issue is to keep the fluid functioning properly under repeated heavy braking.

 

Thanks. Never knew brake fluid would contribute to brake fade in a normal street application. Always thought it was merely the brakes overheating. That's what I was asking.

 

To me paying an absurd dealer price for a brake fluid flush is overkill. Sure there is some risk, but when is the last time you heard of any vehicle, Porsche or otherwise, needing a brake system repair under warranty having anything to do with brake fluid? It is such a rarity anymore.

Not suggesting anybody not change their brake fluid, just suggesting paying dealer prices for something really no more difficult than any other car is needless.

Although I guess I can understand after your experience with the sunroof drains. But I would not have let them get away with that one. Especially since it would not be difficult for you to demonstrate you know where the drains are and you cleaned them. Obviously you know for a fact that cleaning the sunroof drains does not prevent the damage you suffered on your car. Based on my experience, if you fought back and showed them you did in fact clean the drains and how you did it, I think they would've capitulated very quickly, except in the case if they really believed that the repairs were due to your negligence. But it sounds like you would have a little trouble convincing them of that.

Fighting the IRS is not always a lost cause. Been there, done that, our company prevailed over the IRS in tax court. Happens more often than they would like you to believe.

 

Cripes people, just buy a motive, a line wrench, and a couple liters of brake fluid. Bleed your dang brakes. Or pay someone to do it. Or don’t. Don’t waste your life obsessing about it from behind a keyboard.

 

Got my brake fluid tester.
Tested my old Jag & was 1-2% moisture.
I'll probably have it flushed again later this year.
Note<3% is still OK per the experts & markings on all such tools.
Due to dry climate, I can go at least 4 years probably 5 & still be < 3% in that car.

My Macan tested <1% & I'm 2 months away from 2 years since last brake flush.

I wonder what % moisture in brake fluid that was changed 2-3 months prior, in a humid climate, like Florida?

I'm guessing it would not still be @ 0% but, IDK.

There must be a lot of cars out there that have never had brake fluid flushed & are >4% moisture & I hope they never have to panic stop behind me

 

What's the percent moisture in a brand new can of brake fluid?

 

0%

The various testers show:
0%
<1%
<2%
<3%
>4%

They all mark the lower 3 results "OK" & mark; < 3% & >4% as BAD.

 

Ideally it is close to 0%.

@iconoclast I think you can safely flush your brake fluid every 3-4 years, although the brake fluid tester may not be always accurate.

 

A query into the necessity of brake fluid flushing. I wouldn't do this on my Macan but I have a 2005 Ford F-150. I've never flushed the brake fluid. instead once a year I'll remove the old fluid in the resevoir, careful not to expose the master cylinter to air and refill with fresh brake fluid. My thoughts are that the new fluid works itself into all the components, and how often you do this, using a baster/syringe kitchen tool, determines the amount of contamination of old fluid in the system. It's so easy and Dot 3 fluid is cheap.

 

That method would be the same as sucking 1/4 of your engine oil out, not changing the filter and putting only 1/4 of fresh oil back into the system.

When the rubber seals in the calipers go bad, and the system is compromised due to moisture the exchange of that small quantity of fluid is not doing much to remove contaminants and moisture.

There are reasons why service is recommended, its not because the manufacturers want you to spend money for no reason, its called maintaining your vehicle.

This is not my opinion, its done for the long term reliability of the braking system.

Think of a glass of milk, you put a small amount of chocolate syrup in that glass, the whole entire color of the milk changes, same thing with brake fluid, you just added clean fluid to dirty and contaminated fluid, its not doing much to mitigate the reasons for changing it.

 

My guesstimate is that I'm replacing at least 75% of the brake fluid when refilling the resevoir (my Ford F-150 has a deep resevoir) and that there is a complete tranfer of the new fluid (now mixed with the old remaining fluid at 25%) through out the entire system. Do it again a few months later and you have a high proportion of good brake fluid in the system. As I stated earlier I wouldn't do it on my Macan, but I'm curious to others opinions on this method as I seems to work for my truck.

 

I do this on my Macan, which has a big brake fluid reservoir.

In fact, Macan/Porsche is no different from most other cars for oil change and brake fluid change, etc. No secrets here at all.

 

I power bleed my Corvettes, its quite simple, suck all the master cylinder fluid out first and replace with clean fluid.


I then bleed the drivers front first, as that empties the master cylinder quickest, then I go to the pass front, drivers rear and passenger rear last.

That is the opposite of what I usually do for a bleed, but with a pressure MOTIV Power bleeder it makes it quick, if I go to the right rear first its a waste of more fluid IMHO than going to the closest and working back to the farthest.

I have a lift and am able to remove all four wheels easily, as my Corvettes have dual bleeders as they apply pressure from both the inside and outside and do not have a standard caliper in which only one side applies pressure and the other side gets pulled not applied.

Its not hard or expensive to do, its about Porsche knowing it was done, its about them not being able to deny warranty

 

Easy to check the moisture content.

It is the contaminants that concern me. Is this a real vs imagined issue?

IDK but, until I read definitive evidence that moisture is the sole issue, I will be paying to flush brake system in my cars.

The question for me is how often?

I flat out do not believe 2 years, regardless of mileage is true. I think the manufacturers do not want to make it complicated.
My best guess is it may be much longer for dry climates & shorter for damp climates.

When you bring in your car for a $100-200 brake fluid flush, I doubt many mechanics are going to tell you: "I tested your fluid & you do not need this service yet."

If I lived in a humid climate, I'd want to test to see how much moisture is in there @ 1 year. Maybe need to flush every 1 year?

 

https://www.cars.com/articles/how-often-do-i-need-to-change-my-brake-fluid-1420680336417/

 

I bleed brakes on all my cars. Pretty easy and cheap. dot 3 and 4 is the same and is very cheap. The hardest part is taking the wheels off. I save the receipts in case of warranty work for all my service I do myself. Here is a link to a DIY I posted with a 911. Same procedure. You can buy different kinds of bleeder tool at harbor freight really cheap to. I do every two years and the pedal usually feels a little firmer to me with the new fluid. BTW I know people with 100K and never changed fluid, LOL. Not me, I drive a Porsche because I like cars, so cheap and easy service is a no brainer.
https://www.6speedonline.com/forums/997/276985-diy-997-2-brake-fluid-flush.html#post3555600

 

This topic has been debated extensively before.

The brake fluid system is a closed system but is also connected, meaning all the fluid is in one connected system, so the fresh fluid in the brake master cylinder/reservoir works its way throughout the whole system, perhaps slowly.

Otherwise, why would there be a brake fluid reservoir at all?

 

As the brake pads wear the pistons in the caliper move further out increasing the volume of fluid required in the system. Also rotor wear adds to the requirement for more fluid in the calipers.

There is no return line from any of the 4 calipers back to the master cylinder or the reservoir, how is new fluid from the reservoir getting swapped with old fluid in the calipers?

 

It’s called diffusion as long as the fluid in the system is connected.

I have noticed fresh fluid in the reservoir gets dark/dirty after a while. Then you just keep exchanging the fluid in the reservoir with new fluid and it will stay clean after a few cycles.

It’s easy to do and everyone can do it without using any tools. It may not be as thorough as bleeding but it works.

 

Diffusion, l have difficulty believing it would be possible for the new fluid in the master cylinder to travel through brake lines and hoses with an internal diameter of maybe 1/16” and make it all the way through the lines, through the abs unit, through to the calipers ,from one side of the caliper to the other side of the caliper ( front) or all the way to the rear caliper, maybe 4 meters of brake line and back to the master cylinder to exchange new for old fluid. Yeah, right.

 

Agree 100%. No question changing the fluid in the master cylinder only is better than nothing, but I don't believe for a second that most of the moisture and contaminants present by the wheel cylinder furthest away from the master cylinder are at all likely to make it back to the master cylinder, even over a long period of time.

 

It is amazing how magical fluid can be. Believe me!

Next time before you drive, notice the fluid level in the brake fluid reservoir. After a hot run meaning you use the brakes a few times during the drive and look at the fluid level again.

I bet you will see the level changes, usually increases. That means the brake fluid has traveled throughout the system.

 

It is amazing how magical fluid can be. Believe me!

Next time before you drive, notice the fluid level in the brake fluid reservoir. After a hot run meaning you use the brakes a few times during the drive and look at the fluid level again.

I bet you will see the level changes, usually increases. That means the brake fluid has traveled throughout the system.

Expansion, after driving on a hot day, is normal for any type of fluid, but it does not mean the brake fluid has circulated the brake system.

 

Diffusion comes after expansion since all fluid is connected in the system.

 

I happened to be at our local indy in the past hour picking up one of our vehicles, and I asked the owner about the idea of just replacing the brake fluid in the master cylinder repeatedly versus bleeding at each wheel. This is a guy who is been a German car specialist for more than 25 years.

I mentioned the concept of diffusion, and his response was that by definition it tells you that you are never getting out all of the old bad brake fluid no matter how many times you change the fluid in your master cylinder only. So you are never achieving the desired result.

He mentioned in all his years of being in the business he has never heard of one professional nor one vehicle manufacturer that recommends replacing brake fluid in this manner, and he doesn't understand why anybody would resort to this given that the traditional method of bleeding at each cylinder is so easy and elementary.

To quote him "brakes are not a place for taking shortcuts".

Of course we are all free to do whatever we want to our vehicles, but it's certainly not a shortcut I am going to risk taking.

 

FWIW, I've been a HPDE instructor for over 35 years. Without fail, no further out than 3 days before an event, I will bleed my brake system with a MOTIVE Power Bleeder. I have never lost my brakes at an event. Porsche recommends bleeding the system every two years. As mentioned previously, this allows for the removal of moisture. Don't risk your life or others by not performing this simple, relatively inexpensive procedure.

 

+1 on the motive power bleeder it’s so easy. I was dreading the brake fluid changes as well and then I got the power bleeder and the motive brake fluid catch cans. It’s such a breeze now and old fluid is caught in the cans so really makes the process a lot cleaner.

 

HI...Im wondering why these cars need to have the brake fluids changed so often...never heard of this requirement in other modern cars and have never had it done in other newer cars that i have owned ....

 

DOT4 fluid absorbs water over time, and that causes steel parts to rust. A three year cycle is cheap preventative maintenance. Why don't many manufacturer's recommend this? Your guess is as good as mine.

A brake fluid tester is an inexpensive tool that reports percent water in the fluid. It takes ten seconds to sample the fluid in your master cylinder. If it's more than 1%, change out the fluid.

 

Just don’t do what I did by replacing OEM brake fluid with ATE 200 on my Macan. I figured what is good on my 987 is good on the Macan. Nope! Causes massive pedal squeak coming from master cylinder. Stick with OEM or Pentosin Super Dot 4.

 

I've used ATE 200 on Porsche cars for years, and years in the life of a Porsche tech means a lot of Porsche of all models and years and never experienced what you describe.
Something went wrong in there but I can guarantee you that it has nothing to do with the ATE 200.

 

Just use good quality low viscosity brake fluid. It’s not rocket science.

 

Most cars use DOT 3 brake fluid, which is lower performance but also less prone to water absorbance.

 

I didn't see it mentioned in the posts above concerning brake fluid water absorption, so I am posting this note.

Recall that brake fluid will float on top of water if they're in the same system. With that in mind, please realize that
testing the brake fluid in your Macan's brake fluid reservoir will tell you NOTHING about the moisture (read: WATER)
present in the system at the calipers, the lowest level in the system and where water will accumulate first.

If you've heard of "frozen" caliper pistons these are caused by excessive moisture present at the calipers. Eventually
the water causes corrosion between the caliper pistons and their bore.

Another item to bear in mind is water has a much lower boiling point than brake fluid. Repeated heavy braking will result
in water compromised brake fluid boiling before it otherwise would. Once the brake fluid has reached that state the
driver recognizes it when the brake pedal travels all the way to the floor with little to no noticeable braking to the vehicle's
speed .


NOTE: DOT3 brake fluid typically has a lower boiling point than DOT4 brake fluid. It is considered lower performing.

 

I can't speak to SL6 but the Porsche spec is low-viscosity... so I stand by Pentosin LV or Porsche genuine. You'll need two liters to flush it well.