See Figure 1
Check the levels of brake fluid in the brake master cylinder reservoir(s) every 2 weeks. The fluid should be maintained to a level not below the bottom line on the reservoirs and not above the top line. Any sudden decrease in the level in any of the reservoirs indicates a probable leak in that particular system and should be checked out immediately.
When making additions of fluid, use only fresh, uncontaminated brake fluid meeting or exceeding DOT 3 standards. Be careful not to spill any brake fluid on painted surfaces, because it eats paint. Do not allow the fluid container or master cylinder reservoirs to remain open any longer than necessary; brake fluid absorbs moisture from the air, reducing its effectiveness and causing brake and clutch line corrosion.