1997 Chevrolet Astro Owner's Manual - Page 286

Thermostat Engine coolant temperature is controlled by a thermostat in the engine coolant system. The thermostat stops the flow of coolant through the radiator until the coolant reaches a preset temperature. When to Check Power Steering Fluid It is not necessary to regularly check power steering Power Steering Fluid 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 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. What to Use 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. 6-30