smichael

My dealer is pushing me to get a brake fluid flush 2 years after my 30K service (but only about 6K milage). Claims the fluid could crystalize.

Necessary or just a service marketing push?

gota911

Not a service marketing push.

Brake fluid absorbs moisture, which in turn will lower the boiling point of the brake fluid by as much as 30%. The excess water moisture can cause valves to corrode and stick. The moisture can create a rusty sludge that can clog the valves and pistons in the brake system.

But don't take my word for it, check out these links. They are worth 5 to 7 minutes of reading.

http://www.brakefluidtester.com/downloads/clean.PDF
http://www.type2.com/library/brakes/brakef.htm

ivangene

Awe, I was hoping you would do it for me

JW911

It should be done with some frequency, but every 2 years is probably overkill for street driving. I've done it as a warranty precaution. I do it myself. Takes less than an hour and costs $12 for the fluid. I don't even need to take off the wheels. I can reach both bleed valves through the wheel spokes. Probably not possible with your wheels. Never heard of brake fluid crystalizing.

gota911

OOPS!!

SH || NC

'Every 2 years' has been the factory service interval for my other vehicles [Audi/Lexus]. I would have it done.

Don't have it with me - what's the OM say? I think every 2 years.

himself

The braking system is one of the most important operating systems of the car. An ounce of prevention and all that jazz. Besides, it's not that expensive, even if the stealer does it. I would hate to find out the hard way that he's right about crystalizing - although I suspect he's wrong...

-td

1999Porsche911

For the average driver (non track) once evry 4 - 5 years is more than enough.

wwest

Would someone explain to me how, in a SEALED system designed to sustain pressures of up to 3000 PSI, the brake fluid will absorb enough mositure to compromise the braking capability in less than 10 years or 100,000 miles..??

Another case of the dealers promoting "urban legends" in order to line their pockets.

1999Porsche911

The amount of moisture absorbed by the brake system is greatly exagerated, especially in today's cars. Bleeding the system or removing the cap on the resevior allows moisture in. Any air space in the system, such as in the resevior, contains moisture.

Other than an opening on the non pressurized side of the system, if you are absorbing moisture in your brake system, then it is also leaking fluid.

dallison28

moisture builds up in the system from condensation in the reserviour. This moisture will lower the boiling point and will allow the brakes to fade at a much quicker rate compared to newer fluid. Brake fluid should be changed around the factory intervals, but i would prob say 3-4 years and 30-40k would be sufficient for most vehicles. I flush the brake fluid in my vehicles myself. It is pretty easy and the wife usually helps to depress the brake pedal.

With todays systems, as someone posted are pretty well sealed, but again b/c of the close proximity to the motor and location in the engine bay, will get some condensation.



I have only had cars as new as 2002, so things may have really changed.

SH || NC

If its the 'systems' that are so well designed and sealed, then why use different fluids and maintenance intervals for track vs. street?

I've always been told that its because track brake fluid is more hygroscopic, and absorbs moisture more quickly than 'steet' brake fluid.

What's correct?

In my case, I'm sticking to the OM and warranty guidelines.

1999Porsche911

The increase in the "DOT" specifications over the years has increased the boiling temperature of the fluid. Track brake fluid gets much hotter than street fluid.

Palting

Good point about a closed system. Is that little pocket of air in the reservoir enough to "moisturize" the whole system? Maybe not.

I would think that changing the fluid has more to do with degradation. Anything over time degrades. The brake fluid is continually pressurized/not pressurized, heated/cooled, pulled in and out of little spaces and tubes. I am sure it breaks down in time. In 2 years? Maybe, maybe not. Bleeding the brakes is a cheap enough thing to do I'd rather not test it.

Tippy

I will give you my personal story. I was at the drag strip running my '87. There are 2 turn offs for the end of the track. Well me, thinking "hey, I got a Porsche, I can make the first turn off from over 120 MPH". I did but once I turned and tried to apply the brakes for a second time, the pedal went to the floor.

I was baffled because the pedal soon built pressure back up. I was telling my Dad about it and he said "duh, you boiled the brake fluid".

Knowing my friend hadn't changed it in years, he was spot on. The moisture builds up and displaces the fluid which can easily boil causing air pockets.

Not good for hydraulic systems needless to say......