2000 GMC Yukon Owner's Manual - Page 327

NOTICE: If you use an improper coolant mixture, your engine could overheat and be badly damaged. The repair cost wouldn't be covered by your warranty. Too much water in the mixture can freeze and crack the engine, radiator, heater core and other parts. If you have to add coolant more than four times a year, have your dealer check your cooling system. Checking Coolant The coolant surge tank is located on the passenger's side of the engine compartment. NOTICE: If you use the proper coolant, you don't have to add extra inhibitors or additives which claim to improve the system. These can be harmful. CAUTION: Turning the surge tank pressure cap when the engine and radiator are hot can allow steam and scalding liquids to blow out and burn you badly. Never turn the surge tank pressure cap -- even a little -- when the engine and radiator are hot. The vehicle must be on a level surface. When your engine is cold, the coolant level should be at the FILL COLD mark. 6-24