When do we change brake fluid?

I think it was at the 40K mile mark according to some post I saw somewhere. Anyway I'm at 40K on an 05 XJR and thinking it's time.

Any help?

 

Tarheal, it is recommended that you swap out the brake fluid ever 2-3 years. If you put a lot of miles on your car, then you may want to do it sooner. It is more of a time issue than a mileage issue. What causes the brake fluid to go bad is either exposure to moisture (the cap on the reservior needs to breathe and therefore lets moisture in there) or excessive brake heat (just below the point where your rotors are glowing red and up in temperature). Most people don't drive their cars hard enough to reach the temperature aspect, but they do live in areas where it gets humid and whatnot.

If you want to do a quick check, connect up a tube to any of your brake calipers on the bleed port. Point the tube straight up with atleast 2 feet of tubing. With the aid of a second person, have them press on the brake pedal as you crack open the bleed port. You want to let about 6" or so of fluid into the tube, then you can shut the bleed port. What you are wanting is essentially clear fluid there. if it is a light green color, then that is acceptable too. But, if you are getting a darker color green, then it is time to swap out the fluid.

if you need some pointers on how to do it, let me know. I have a little rig that is easy to create that allows you to do the brakes by yourself and only costs you $5 plus the cost of the fluid.

 

Thanks Thrermo, the fluid was a dark amber color so I went ahead and removed and replaced it using the positive pressure method and my air compressor. Brakes are noticeably firmer. Slight mushie feel is gone.

Not a complex job but removing and replacing the tires with my old back and the service jack was a bitch. Don't look foward to doing that again.XJR tires and wheels are really heavy!