1995 GMC Yukon Owner's Manual - Page 313

When to Check and What to Use 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 Checksand Services" and "Recommended Fluids and Lubricants" in the Index. How to Check The proper fluid should be added if the level does n o t reach the bottom of the diaphragm when it's in place i n the reservoir. See the instructions on the reservoir cap. Rear Axle When to Check and Change Lubricant Refer to the Maintenance Schedule to determine how often to check the lubricant and when to change it. See "Scheduled Maintenance Services" If the level is below the bottom of the filler plug hole. you'll need t o add some lubricant. Add enough lubricant t o raise the level to the bottom of the filler plug hole. 6-3 1