Kevhunts said:
The USA manual states to rebuild clutch & brake master cylinders every two years and to replace the hoses every four.
Has anybody actually done this or does this seem like overkill?
Read your car manual for this stuff. It's often the same. Virtually no one replaces brake lines every two years, as recommended by oems. 30 year old cars often have the original brake lines... seldom a problem. Same materials involved, same brake fluids involved. I never replaced the brake lines on my FJR over 9 years and 160k miles. I did do annual fluid changes though, an do that with the S10 too. Never had an issue with the outstanding brakes of the FJR other than pads and rotors... and fluid changes.
Brake fluid is hygroscopic. This just means that over time, it absorbs water and this reduces the boiling point. Listed as dry and wet on most fluids. Dry is virginal fluid just out of the can. Wet is pretty much everything else. More water content, quicker to boil and cause loss of function. Excess water content can and does cause corrosion in other parts of the brake system and can cause ABS valve blocks to become useless if they never get cycled and that old fluid stays in the valve block.
