Four Wheel Drive - GMC 2000 Yukon XL Owner's Manual

The proper level for the 1500 Series is from 5/8 inch
to 1 5/8 inch (15 mm to 40 mm) below the filler plug.
The proper level for the 2500 Series is from 0 to 3/8 inch
(0 to 10 mm) below the filler plug. Add only enough
fluid to reach the proper level.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See "Recommended Fluids and
Lubricants" in the Index.
Four Wheel Drive
-
Most lubricant checks in this section also apply to
- -
four wheel drive vehicles. However, they have two
additional systems that need lubrication.
Transfer Case
When to Check Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant. See "Periodic Maintenance
Inspections" in the Index.
How to Check Lubricant
Automatic Transfer Case
If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
Use care not to overtighten plug.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See "Recommended Fluids and
Lubricants" in the Index.
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