GMC 1996 Savana Van Owner's Manual page 248

Thermostat
Engine coolant temperature is controlled by a thermostat
in the engine cooling system. The thermoskt stops the
tlow of coolant through the radiator until the coolant
reaches a preset temperature.
When you replace your thermostat, an AC@ thermostat
is recommended.
Power Steering Fluid
When to Check Power Steering Fluid
It is not necessary to regularly check power steering
tluid unless you suspect there is a leak in
the system or
you hear an unusual noise. A fluid loss in this system
could indicate a problem. Have the system inspected
and repaired.
How To Check Power Steering Fluid
When the engine compartment is cool, unscrew the cap
and wipe the dipstick with a clean rag. Replace the cap
and completely tighten it. Then remove the cap again
and look at the fluid level on the dipstick.
The level should be at the FULL COLD mark. If
necessary, add only enough fluid to bring the level up to
the mark.
To prevent brake fluid contamination, never check or fill
the power steering reservoir with the master cylinder
cover off.
What to Use
Refer to the Maintenance Schedule to determine what
kind of fluid to use. See "Recommended Fluids and
Lubricants" in the Index. Always use the proper fluid.
Failure to use the proper fluid can cause leaks and
damage hoses and seals.