GMC 1995 Suburban Owner's Manual page 315

How to Check Lubricant
If the level
is
below the bottom of the filler plug hole, you'll need to add
some lubricant.
If the differential is at operating temperature (warm), add enough lubricant
to raise the level to the bottom of the filler plug hole.
I f the differential is cold, add enough lubricant to raise the level to 1/2 inch
(
12 m n ) below 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.
Engine Coolant
The following explains your cooling system and how to add coolant when it
is low. If you have a problem with engine overheating, see "Engine
Overheating" i n the Index.
The proper coolant for your vehicle will:
Give freezing protection down to -34°F (-37°C).
Give boiling protection up to 262°F (128°C).
Protect against rust and corrosion.
0
Help keep the proper engine temperature.
Let the warning lights and gages work as they should.
What to Use
Use a mixture of one-half clecur
wcrter
(preferably distilled) and one-half
antifreeze that meets "GM Specification 6038-M," which won't damage
aluminum parts. You can also use
a
recycled coolant conforming to "GM
6-33