DOT 3 and DOT 4 brake fluid is "hygroscopic." It is so prone to water contamination and absorbs humidity right out of the air. This is why it is always recommended to use fresh fluid. If there is any doubt about the fluid you are using, buy new fluid.
Use only fresh DOT 3 or DOT 4 specification brake fluid from a sealed container. If you are unsure of the condition of the fluid (whether or not it has been tightly sealed or how long it has been in storage), use new fluid rather than taking a chance of introducing moisture into the system. It is critically important that the fluid meet the specification so the heat generated by modern disc brakes will not cause it to boil and reduce braking performance. Fluid must be moisture free for the same reason.
See Figures 1, 2 and 3
Brake master cylinder fluid level should be checked every few weeks for indication of leaks or low fluid level due to normal wear of the brake lining.
On all Hondas, there is a fill line (or MIN/MAX lines) on the brake fluid reservoir(s) as well as an arrow on the reservoir cap(s) which should face forward when installed. When adding brake fluid, the following precautions should be observed: