I replaced the thermostat just now and as I suspected it was partially defective. The car runs at a steady 80-82c just like I thought it should. Anyone with a lower reading, I think you have a defective thermostat. Easy job!

I left the green coolant in, I asked how much a gallon was at the dealer.. $20!! Over doubled the price when I last bought it.. the parts guy said a chemical that is used to make it is in short supply.. sounds like BS to me.