Brake fluid question

when in doubt, I suggest you follow the manufacturer's advice as I do. I think the failure mechanism is a matter of time, not a matter of miles driven.

I found this text on justbrakes.com (no affiliation, just did a google search)

" Brake fluid is formulated to tolerate moisture absorption, control rubber expansion and corrosion, and acts as a lubricant. It also must not boil or freeze in brake systems over a wide range of operating temperatures. The level is checked occasionally, but very seldom is brake fluid completely replaced unless the vehicle's braking system undergoes a major overhaul. Most technicians know that brake fluid deteriorates with age due to moisture and contamination. DOT 3 and DOT

4 brake fluid are polyglycol based. This glycol ether blend of fluids is "hygroscopic" which means it attracts and absorbs moisture. This process takes place every time you take the cap off the container or check the fluid in the master cylinder reservoir. Moisture is even absorbed through microscopic pores in rubber seals and hoses in the brake system. Also keep in mind when you use your brakes, heat is generated at the friction contact points. As your vehicle sits, your brakes cool down. Therefore, over a period of time the heating and cooling action of your brake system will condense moisture in the closed hydraulics system. DOT 3 and DOT 4 brake fluid will absorb that water and keep it from effecting hydraulic components and helps prevent or at least slow down the corrosive effect. Even though brake fluid absorbs moisture, it cannot continue to absorb it indefinitely, which is why it is recommended that you flush the system and refill with fresh brake fluid once a year or every 12,000 miles"

btw, once a year is not necessary... this advice is coming from a company that provides this service so you figure their motives.

If you do this service, make sure you remove as much old fluid as you can get from the reservioir before you start. You do not want to push dirty fluid into your braking system. I think you may be able to get this done for under $40 and that would be money well spent. If you really want to do this yourself, I suggest you purchase the Motive brake bleeder from germanautoparts.com. (this what I did)

good luck!

Mark

Conventional wisdom: change the brake fluid every 2 years, as the fluid tends to absorb moisture over time. This can corrode system components and lead to premature deterioration of the braking system. The absorbed moisture also tends to reduce boiling point of conventional brake fluids, which could lead to fluid vaporization under severe use. Hydraulic brake systems depend on the relative "incompressibility" of liquid brake fluid to transmit braking forces within the system; gaseous fluid is much, much, much, more compressible and will not transmit the loads effectively.

In my experience, this is very conservative advice, but brake fluid and an hour or two of labor every two years is cheap. Your life, and that of your passengers and other drivers, is priceless.

I'd follow it. With my '91 GTI I didn't do that and ended up having to get a new master cylinder at 110K miles. Brake fluid flushes aren't that pricey. Ever since that M/C change I've followed that routine.

Mileage is much less relevant than age on Brake fluid - it absorbs moisture over time & 2 years is the limit on pretty much any fluid/car. Change it & I think you'll find you have a much firmer pedal & better brakes afterwards.

I.

With brake fluid it needs to be replace, not based on any wear factor, but rather to the fact it absorbs water. That is why you should never save brake fluid after the can is opened. Water in brake fluid can be very dangerous and also can damage brake parts (even more so with ABS)

It's like the rest of the VW manual... it's just there to take up space and waste paper, ink, printing costs.

I understand you point, I do follow the manual. Two years just seemed kinda early. I'll have it down while they are fixing my heated seat since the element wants to melt my leather in a spot. Thanks

Sarcasm's not going to do this guy any good, especially since the question he asks is a good one, and there are many common misconceptions regarding recommended service intervals. Are you here to educate these folks and help them with their problems or to shame them into mindlessly dropping their cars off at their nearest VW dealership every few weeks for unneeded service and a wallet-ectomy?

There is no question in my mind that a little well-applied common sense and hard-earned experience will allow one to extend the manufacturer's recommended service intervals without affecting the car's longevity or sacrificing safety. I wouldn't be so naive to believe that everything in the VW manuals are based on solid technical requirements flowed down from engineering. More often than not, fear of liability drives manufacturers to be very conservative regarding service intervals. And when shorter service intervals undoubtedly boost dealer profits, don't think that the strong dealer lobby (akin to organized crime IMHO) doesn't do their best to keep recommended service intervals as short as possible.

You bet it is.

Brake fluid is hygroscopic, which means it WILL absorb moisture from the air, and the result is that your brake system will corrode internally.

CHANGE your brake fluid, every 2 years, or save up for a rebuild of your brake system.