What amazes me, and please don't take this personally, is that people will spend a lot of money on the actual car, and then not take the manufacturers advice on maintaining it. For £60 (or whatever it is) every 2 years, it is worth it for a bit of piece of mind and the fact a full and complete service history will demonstrate the car has been looked after when selling on.
I found this explanation on another forum:
With time the brake fluid takes on water - you can see this happen by watching the fluid become darker with time (color change is by design and due to water uptake) - as the fluid takes on water, two things happen - first, the boiling point of the brake fluid decreases (the fluid boils at a lower temperature, which will show up as fade under conditions of repeated, hard braking like you might go through at a track) - the second thing which changes is the corrosiveness of the fluid - as it takes on water, it becomes increasingly aggressive towards the caliper and piston - this results in corrosion the end result of which is the caliper seal is no longer able to seal the bore (fluid gets around it), getting fluid all over the place (this is a gradual thing) - this is why if you live in a humid region and have been neglecting the brake fluid, you need to hone out the cylinder bore (so that it is uniform and smooth) or replace the pistons, or both.
Nothing but a money maker for dealers the 2 year rubbish. The fluid will be ok for 5 or more years if you do not track the car and boil the hell out of it. You can tell when it needs changing as the brake feeling starts going spongy. It will not make the brakes fail suddenly like some usually say. Mine wont be changed until it is needed, I have had cars in the past that have never had a brake fluid change.
