Use brake fluid meeting DOT 3 standards only.
See Figures 1, 2 and 3
The brake fluid reservoir on top of the master cylinder is clear so that you can check the fluid level without removing the top. If the level falls below the low mark, wipe off the cap and the outside of the reservoir, then remove the cap and refill the reservoir up to the MAX mark.
As the vehicle ages, the presence of brake fluid in the reservoir will sometimes leave a residue that makes it difficult to read the fluid level reliably through the plastic. It is wise to occasionally check the fluid level by removing the cap to make sure you can accurately determine whether or not additional fluid is required. Always be careful to keep dirt out of the system when removing the cap.
It is normal for the level to drop gradually, as fluid takes up lost volume in the system occurring due to brake pad wear. A sudden loss of a significant amount of fluid should be investigated immediately. The system must be inspected thoroughly and all causes of leakage repaired.
Follow these same procedures for checking the fluid level in the clutch master cylinder on the vehicles equipped with a hydraulic clutch.