i have a 2003 impala 3.4l 163,000 miles. i just bought this car about a week ago and just checked the coolant and inside the radiator is a bunch of nasty brown crap. im guessing this is because of the dexcool antifreeze. the car isnt overheating but the temp gauge does go up when setting at a red light or a drive threw or setting in park, but goes back down when i start driving and the radiator has airflow to it. so im wondering if i should flush it real good and put regular green antifreeze in it or flush it and keep using dexcool. ive always herd bad things about dexcool and would really rather use regular antifreeze. but ill see what you guys have to say. thanks for any help!