Do you replace the brake fluid in your car?

[neeeeeeeeeek 10]

OK, so I get that it absorbs water, but isn't it a sealed system? If water could get in, then it makes sense the fluid could get out. If it got out, there would be a loss of pressure, resulting in loss of brakes. So, unless the brakes are leaking, how does it get to absorp water?

[Dardandec 32]

OK, so I get that it absorbs water, but isn't it a sealed system? If water could get in, then it makes sense the fluid could get out. If it got out, there would be a loss of pressure, resulting in loss of brakes. So, unless the brakes are leaking, how does it get to absorp water?

 

Its not fully sealed through the reservoir cap as such, if it was you would get a vacuum and no fluid would be allowed into the master cylinder and then forced into the rest of the system.

 

Most systems including hydraulic clutch systems have a ventilated cap and a large rubber cap that acts as a diaphragm to prevent vacuum and compression for that matter on the reservoir side of the system. Over time moisture is absorbed through this setup.

[Obelix 11]

As has been said by others brake fluid absorbs water and should be changed before excess water content in the fluid causes brake failure. However the two year service interval recommended by nearly all manufacturers is for most people is a bit over the top. I bought a brake fluid tester which gives an indication of moisture level in brake fluid and tells you when the fluid actually needs changing, my wife's car is five years old and the tester still shows minimal moisture content. My car on the other hand showed excessive moisture levels, I am currently overhauling the brakes and have already spent £400 on replacement parts.

 

It depends on what you do. In the Alps, you want to swap it every two years as you have all the long descents of course. In the UK, perhaps 5 years is fine unless you tow a caravan regularly. The manufacturers will pick the harshest duty recommendations as they dont know where the cars are going to be sold and used of course.

[alchresearch 214]

Its not an expensive job. I normally change it on a "new to me" car if there's no paperwork evidence showing its been done.

[Cyclone 10]

NO.............. I've had my car 13 years and never had the brake fluid changed.

 

This advice is akin to the following;

 

"Should I ever service my {vital piece of live saving kit}"

"No, I've never done it and it's not killed me".

 

The key word missing from the answer is "YET".

[Obelix 11]

And when it does go wrong - assuming they are still alive to tell the tale - they whine about the manufacturer skimping and saving pennies on it because it didn't lasst long enough...