Yesterday, I drove about 100 miles. 50 mile trips non stop. It was on the freeway, and my average speed was around 75 to 80, peaking at 90, so my engine was really moving. I notice coming home that my temp is really high, like well over 200. With the new thermostat I got in, the car never went over 200. I got home and let it sit for about a half and hour, and then drove to the bank, which was only a mile away. It was still over 200. Probably around 205 or 210. Then I let it sit for about 4 hours. It hovered around 200. Today, I drove it for a little while, and it was fine.
I don't know why it got so hot. Could it be in the radiator? Or the coolant?