2006 Hummer H2 Owner's Manual - Page 374

How to Check Lubricant What to Use Refer to the Maintenance Schedule to determine what kind of lubricant to use. See Recommended Fluids and Lubricants on page 6-12. Four-Wheel Drive Transfer Case It is not necessary to regularly check transfer case 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. Refer to the Maintenance Schedule to determine how often to change the lubricant. See Scheduled Maintenance on page 6-4. To get an accurate reading, the vehicle should be on a level surface. When the differential is cold, the proper level is from 5/8 inch to 1-5/8 inch (15 mm to 40 mm) below the bottom of the filler plug hole, located on the rear axle. Add only enough fluid to reach the proper level. 5-44