Locate the drain plug and Drain the radiator.
once it is almost empty, fill up the Coolant resevoir with water from the garden hose and keep the drain plug off and this will get most of coolant out. Wait until it starts coming out clean.
Put your radiator drain plug back on and fill with your choice of coolant flush cleaner and water from the hose. Follow the directions on the bottle, more than likeley it will say to run the vehicle for about 10 - 15 min. Put the heat on MAX so the heater core is getting the flush cleaner running through it as well.
Turn the vehicle off and drain once again.
Disconnect the hoses from the water pump, not the firewall. The plastic fittings on the firewall tend to break very easily. Run the water hose through the heater core hoses to flush that out completely and once again wait until the water runs clear. While you are there you may want to replace your thermostat. I purchased one from my local autoparts store that came with a new housing and seal.
Once everything has been drained and water has been running clear through everything, you are now ready to fill up with Dexcool. This is the orange coolant, NOT green. You have your choice of getting the 50/50 pre-mixed, or mixing yourself. Either way fill it up and turn the vehicle on again and put the heat on MAX again and leave the radiator cap off so the cooling system and burp itself for a little while. This can take a little bit but shouldn't be too long.
Cap the resevoir and you should be good to go!
