Rocket

Not being one for changing anything for the sake of it what is the life expectancy of Porsche DOT 4 specification brake fluid, when the car is used in the main for trackday/circuit use. I had assumed Porsche would have specified something more race orientated, but to my surprise when I enquired DOT 4 is seemingly the stuff that was used at the last service.

After about 900 miles of circuit driving (6 trackdays) I am experiencing no noticeable deterioration in either brake pedal feel or braking performance (fade etc).

Without drawing the obvious conclusion that I don't brake hard enough , is this the experience of others and normal for Porsche brakes, or am I likely to run in to a problem (if not armco) fairly shortly?

Rocket

Jim Michaels

Good question; especially considering your "so far, so good" experience. Some of the Driver's Ed inspection forms we get over here in the colonies specify brake fluid should be no more than 3 months old; up to 6 months if it's ATE Blue or Amber. Some change even more frequently. Your experience with OE pads and fluid is a little better than mine. I used to get some brake fade after the brakes heated up on the track. I switched to ATE fluid and Performance Friction pads and haven't experienced any fade since. But I'm not as hard on brakes as some are either.

Steve Weiner-Rennsport Systems

Rocket:

Our recommendation is to change/flush the brake fluid annually, at minimum.

There are many variables at work here such as how many track events you participate in, what your brake operating temperatures are, ambient temperatures and humidity, and several others.

Using the ATE family of brake fluids, Type 200 or Super Blue, the above recommendation will work OK for the majority of people.

Bear in mind though, that brake pedal "feel" is no indication of the health of your fluid. There are special testers made by Leica and some others that test for moisture content of brake fluids.

You will get little or no warning when the fluid boils due to accumulated moisture, and given the low price of such products, the best thing is to be proactive and change it frequently.

"An ounce of prevention is worth a pound of cure" in this case, and the folly of not changing brake fluid often enough when used for track events can be VERY expensive.

STLPCA

Rocket
Ran across these articles some time back which address some of your concerns. It seems brake fluid begins to degrade as soon as it's out of the container (or before if it's from a plastic container).

General Brake Fluid Article

Comparisons of Brake Fluids

Rocket

Thanks for your helpful responses.

Perhaps it is therefore prudent just to bleed them through for now, and replace with higher grade fluid at the next service.

Good to have the DOT rating explained too.

Rocket