Rear Axle; Front Axle - GMC Yukon XL Denali 2005 Owner's Manual

Rear Axle

When to Check 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.
How to Check Lubricant
To get an accurate reading, the vehicle should be on a
level surface.
5-48
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. Add only enough fluid to reach the proper level.
What to Use
To determine what kind of lubricant to use, see
Recommended Fluids and Lubricants on page 6-12.

Front Axle

When to Check and Change Lubricant
It is not necessary to regularly check front 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.