2006 Hummer H3 Owner's Manual - Page 311

Rear Axle When to Check and Change Lubricant It is not necessary to regularly check rear axle fluid unless you suspect there is a leak or you hear an unusual noise. A fluid loss could indicate a problem. Have it inspected and repaired. To get an accurate reading, the vehicle should be on a level surface. If the level is below the bottom of the filler plug hole, located on the rear axle, you will need to add some lubricant. Add enough lubricant to raise the level to the bottom of the filler plug hole. What to Use See Recommended Fluids and Lubricants on page 6-12 to determine which kind of lubricant to use. How to Check Lubricant Front Axle It is recommended that the front axle fluid be checked and filled by your dealer. 5-45