Buick Century 2003 Owner's Manual page 237

When to Check Power Steering Fluid
It is not necessary to regularly check power steering fluid
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
Turn the key off, let the engine compartment cool down,
wipe the cap and the top of the reservoir clean, then
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.
What to Use
To determine what kind of fluid to use, see Part D:
Recommended Fluids and Lubricants on page 6-16 .
Always use the proper fluid. Failure to use the proper
fluid can cause leaks and damage hoses and seals.
When the engine
compartment is hot, the
level should be at the
H (hot) mark. When
it's cold, the level should
be at the C (cold) mark. If
the fluid is at the ADD
mark, you should add fluid.
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