See Figures 1, 2 and 3WARNING
Do not use old brake fluid that has been sitting on your shelf for any length of time. Brake fluid is hygroscopic, meaning it acts like a sponge to soak up water vapor from the air. Old brake fluid is likely to be water-contaminated which will have a detrimental affect on your braking system.
The clutch master cylinder is very similar to the brake master cylinder. The hydraulic fluid reservoirs on these systems are mounted on the firewall. Fluid level checks are performed like those on the brake hydraulic system. The system should be inspected periodically when other underhood services are performed. The proper fluid level is indicated by a step on the reservoir. To prevent contamination of the system with dirt, ALWAYS clean the top and sides of the reservoir before opening. Remove the reservoir diaphragm before adding fluid, and replace after filling. Keep the reservoir topped up with DOT-3 fluid; do not overfill.
Do not allow any petroleum base fluids to enter the clutch hydraulic system, this could cause seal damage.