2011 Chevrolet Silverado 1500 Regular Cab Owner's Manual - Page 430

10-24 Vehicle Care The vehicle must be on a level surface when checking the coolant level. Check to see if coolant is visible in the coolant surge tank. If the coolant inside the coolant surge tank is boiling, do not do anything else until it cools down. If coolant is visible but the coolant level is not at or above the FULL COLD mark, add a 50/50 mixture of clean, drinkable water and DEX-COOL coolant at the coolant surge tank, but be sure the cooling system is cool before this is done. { WARNING You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine. Notice: This vehicle has a specific coolant fill procedure. Failure to follow this procedure could cause the engine to overheat and be severely damaged. The coolant level should be at or above the FULL COLD mark. If it is not, there may be a leak in the cooling system. How to Add Coolant to the Coolant Surge Tank for Gasoline Engines If the vehicle has a diesel engine, see "Cooling System" in the Duramax Diesel Supplement for the proper coolant fill procedure. { WARNING An electric engine cooling fan under the hood can start up even when the engine is not running and can cause injury. Keep hands, clothing, and tools away from any underhood electric fan.