Four-wheel drive, Four-wheel drive -59 – GMC 2006 Sierra User Manual
Page 471
•
The proper level for the 2500HD with the 6.6L diesel
engine (RPO LLY) or 8.1L V8 engine (RPO L18), and
3500 Series is from 0.6 to 0.8 inch (17 mm to 21 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 (Gasoline Engine)
on page 6-14.
Four-Wheel Drive
Lubricant checks in this section also apply to these
vehicles. There are two additional systems that need
lubrication.
Transfer Case
When to Check Lubricant
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.
How to Check Lubricant
Manual Transfer Case
5-59