2004 GMC Canyon Owner's Manual - Page 288

Hydraulic Clutch (Manual Transmission) The hydraulic clutch linkage in your vehicle is self-adjusting. The clutch master cylinder reservoir is filled with hydraulic clutch fluid. The hydraulic clutch fluid reservoir cap has this symbol on it. When to Check and What to Use It is not necessary to regularly check clutch fluid unless you suspect there is a leak in the system. Adding fluid won't correct a leak. A fluid loss in this system could indicate a problem. Have the system inspected and repaired. Refer to the Maintenance Schedule to determine how often you should check the fluid level in your clutch master cylinder reservoir and for the proper fluid. See Owner Checks and Services on page 6-9 and Recommended Fluids and Lubricants on page 6-13. How to Check and Add Fluid The proper fluid should be added if the level does not reach the bottom of the diaphragm when it's in place in the reservoir. See the instructions on the reservoir cap. 5-24