Yeah, I know, the guy's got a lot of questions...

My car is about 3 years old and hasn't had a brake fluid change. I check the brake fluid in its little clear reservoir and it is clear and clean as honey. Is there a visual check for brake fluid or should I simply change it as a maintenence item regardless? Car has 20k miles.
Thanks.

 

Visual check won't tell you a thing. I would do a fluid change, it is cheap insurance against the fluid failing when you need it the most. I change my fluid about 7-8 times a year (with regular track use).

 

+1

Brake fluid contamination will happen with time. It absorbs water and hold it in suspension, changing its properties. Moisture seeps into the brake system continuously through the various seals and microscopic pores. Over time the fluid can reach wet boiling point easily. Because this happens gradually, most drivers won’t the problem until its too late.

 

The amount of water that can get into brake fluid is an old wive's tale. It is good to change your fluid based on your driving style due to break down of the fluid but not because of water contamination. For a street car, every 4 years is more than enough and every 6 years will do no harm or reduce braking performance.

 

Ah, a healthy debate, I like that. I would think if I were contemplating a trip to the track I might do it to ensure a low boiling point. I thought I've read about people inspecting the fluid and noting that it actually "looked" contaminated or burned. Mine is clean and clear as honey.

 

Agreed, but there is no way for the OP to know how the previous owner drove this car. Cheap insurance would be to change it and then he will know what condition it is in.

 

I must be an old wife then!

If it wasn't an issue, why do manufacturers bother checking dry versus wet boiling points?

 

I doubt that people can tell what condition it is in, unless it is really bad. Besides the fluid at your calipers is not the same as the fluid in the reservoir. You just spent a ton of money on a new (to you car) what is a little extra to make sure it is in top working order?

 

True enough, true enough...

 

Rather than repeating a false condition, why not explain exactly how a substantial amount of moisture enters a sealed system without also expelling fluid. Don't bother GOOGLING it as there is in excess of 2,000 pages that repeat the same statement: "through the brake master cylinder reservoir and permeable brake hoses".

I guess Tupperware can seal out moisture but a brake system cannot?


There sure are alot of people who don't know the definition of permeable.

 

LOL...So I guess you store your extra DOT4 in tupperware until the next flush.

I love your cynicism. If you have evidence to dispel this wives tale, I'm interested in learning...seriously.

 

Simple proof is to measure moisture content in brake fluid operated in a closed system.. No further evidence is needed.

Why do people accept as fact, something that has no basis. Just because something has been repeated over and over again does not make is so.


Yes. You can store brake fluid in tupperware or any other sealed container without fear of moisture being absorbed. The only moisture that will ever be in the fluid is what was in the air space not taken up by the fluid. Vacuum would eliminate even this moisture.

 

During a heavy track season, when I chew up new pads and replace them before winter, the brake fluid levels from the master will fall slightly to compensate for the additional volume needed. When you open the master cylinder cap, shouldn't I be hearing a vacuum sound if the system were completely sealed?