Always use a brake fluid which meets DOT-3 or DOT-4 heavy duty specifications.
See Figures 1, 2 and 3
The brake fluid level should be check at regular intervals. Drain the brake fluid and replace it at 30,000 mile (48,300 km) intervals. When the vehicle is frequently used in humid conditions or mountainous areas, change the brake fluid at 15,000 mile (24,000 km) intervals.
The brake master cylinder reservoir(s) are made of translucent plastic so that the fluid level may be checked without removing the caps. Check the brake fluid level at regular intervals. If the brake system warning light comes on, stop the car and immediately check the brake fluid level.
If the fluid level in either of the master cylinder reservoir(s) falls below the bottom (MIN) line molded on the side of the reservoir, add brake fluid to bring the level up to the top (MAX) line. Clean the top of the reservoir off before removing the cap to prevent dirt from entering the master cylinder. Pour the fluid slowly to prevent air bubbles from forming. Brake fluid is a good paint remover, so don't spill any on the car's paint.