GMC, antifreeze replacement in Zevulun

GMC, antifreeze replacement in Zevulun.
To replace the antifreeze, the used coolant is first drained into the drain pan through the radiator drain cock. Then the sealed radiator cap is removed so that the remaining coolant can be drained completely. The radiator and expansion tank must be completely free of coolant. The engine block drain plugs and drain valve are closed. After that, a prepared antifreeze and water solution of is poured into the filler neck of the radiator through a funnel.