Monitor the condition and level of coolant in your GMC Sierra regularly. When the coolant begins to degrade, change color or show debris, drain the radiator completely before replacing the coolant. The Sierra provides an easily accessible radiator drain at the base of the radiator. When refilling your engine coolant, use a 50/50 mixture of pure, clean water and anti-freeze for optimal performance.
Raise the Sierra with a jack and position it on a set of jack stands. Allow the engine to cool completely if the truck has been running.
Position a large drain pan or bucket beneath the radiator drain plug. The drain plug on the GMC Sierra is located at the base of the radiator on the driver side of the truck.
Loosen the radiator drain plug with a wrench. Turn the plug counterclockwise to loosen it until coolant flows from the drain.
Allow the coolant to drain completely from the radiator. Replace and tighten the radiator drain plug using a wrench.
