the oil and everything is good. i end up changing the thermostat. it didnt overheat after that. but my old thermostat i tested it. i boiled some hot water, and put my old thermostat in there. The old thermostat end up opening. so im guessing the old one wasnt bad. But for some reason, my car is not overheating with the new thermostat. My new and my old thermostat both look diff. Any clue?