1997 Buick Century Owner's Manual - Page 288

Checking Coolant I If this light comes on, it means you're low on engine coolant. Adding Coolant If you need more coolant, add the proper DEX-COOL@ coolant mixture at the coolnnt wcovev tank, but be careful not to spill it. When your engine is cold, the coolant level should be at the COLD mark or alittle higher. When your engine is warm, the level should be up to the HOT mark or a little higher. If the coolant recovery tank is completely empty, add coolant to the radiator. (See "Engine Overheating" in the Index.) 6-22