GMC 1999 Suburban, Owner'S Manual, Page: 304 / 424

yellow blue
6-24
Front Axle
When to Check and Change Lubricant
Refer to the Maintenance Schedule to determine how
often to check the lubricant and when to change it. See
“Scheduled Maintenance Services” in the Index.
How to Check Lubricant
If the level is below the bottom of the filler plug hole,
you may need to add some lubricant.
When the differential is cold, add enough lubricant to raise
the level to 1/2 inch (12 mm) below the filler plug hole.
When the differential is at operating temperature
(warm), add enough lubricant to raise the level to the
bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See “Recommended Fluids and
Lubricants” in the Index.
Radiator Pressure Cap
The radiator pressure cap must be tightly installed with
the arrows on the cap lined up with the overflow tube on
the radiator filler neck.