50/50 Mix of Zerex G-05 (or equivalent) and distilled water (preferably)....for the final mixture. You can flush it with water and a cooling system cleaner treatment....just make sure you get the proper anti-freeze mixture in the end when you're done flushing. You will have residual water in the system after flushing that can thin the mixture when you do the final refill. You can open the block drain plugs when done flushing to get all the water out...... Or, while doing the final refill, fill it, check freeze point, if too high, open the radiator drain, let a quart or so out at a time while adding pure antifreeze to lower the freeze point, which should be -34F.
Be sure to properly bleed the system while filling using the bleeder valve at the front of the engine, in the top of the intake manifold. Open it regularly during the flush process, and on the final fill, open it, and leave it open until you cannot add coolant anymore, then start the engine, crack it open for a few seconds to let excess air out, then run the engine to operating temp with the radiator cap OFF. Once it his operating temp and the thermostat opens, recheck the coolant level, and top off as needed. Shut it down, let it cool, check the level again.
If this is a 2.7, and your coolant is milky, or super dirty, you might have oil/coolant mixing issues from a bad water pump, or worse, head gasket. Those issues will need to be checked as well.
Last edited by Daytrepper; 09-05-2012 at 08:10 PM.