Brake fluid should meet the DOT 3 specification. Use DOT 4 for heavy duty application such as trailer towing or mountain driving. Use only clear fluid from a sealed container.
Fluid that is exposed to the air will absorb moisture. Water in the brake fluid will cause the fluid to boil and the rubber components to deteriorate. for leaks. Fix and leaks. Then refill the reservoir to the MAX indicator mark.
Thoroughly clean the master cylinder reservoir cap before removing it. Do not let any dirt or foreign material fall into the fluid reservoir.
There is a fluid level switch in the master cylinder reservoir. When the fluid level is low, the BRAKE lamp in the instrument cluster will turn on.
The correct brake fluid level is marked on the left side of the master cylinder reservoir. If the fluid level is below the MIN indicator mark, check the hydraulic brake system for leaks. Fix any leaks. Then refill the reservoir to the MAX indicator mark.