i am replaceing my water pump, and seeing that i am draining all my coolant i would like to go with the green stuff not dex cool what do i have to do , besides replace dex cool with antifreeze

 

Flush the system (radiator, block, and heater core) with your garden hose and drain as best you can, then run a few gallons of distilled water through the block and radiator. When you go to fill the system with coolant, dump in exactly half the system capacity (~6 qts) with straight coolant (whatever your choice), then top off with distilled water. The distilled water doesn't contain any of the minerals that your garden hose may have, extending the life of the coolant.

I'd recommend going to the Prestone All Makes All Models Extended Life coolant.