So I have a daily driven 68 dart with a 225 slant six. For as long as a can remember, normal temp is the gauge reads just above half way in the sweep in the middle of the normal range. The other day on Monday I took the radiator cap off to check the level because i was going to go on a trip (120 miles away) The level was ok so I didn't add any. Since then the gauge is reading at the very low end of the normal range, almost into the cold side. Even after driving the 120 miles and back, it's reading on the low end. Almost a week later and it's still reading on the low end from a dead cold, no matter what i do or how hot it is outside. BTW: NON a/c car and runs and drives fine with no other known problems.