2006 Chevrolet Cobalt Owner's Manual - Page 265

If you have to add coolant more than four times a year, have your dealer check your cooling system. Notice: If you use extra inhibitors and/or additives in your vehicle's cooling system, you could damage your vehicle. Use only the proper mixture of the engine coolant listed in this manual for the cooling system. See Recommended Fluids and Lubricants on page 6-12 for more information. {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 COLD FILL line. Checking Coolant The coolant surge tank is located in the engine compartment on the driver's side of the vehicle. See Engine Compartment Overview on page 5-12 for more information on location. 5-25