I use it only on weekends, mainly - occasionally weekdays after work. Temp gauge has gone slightly above half then down, when you would hear the fan come on. The past 2 days, I took the car for around 1/2 hour drive, including a stretch of around 5 miles at 60 MPH or a little more. The gauge was fine & the car ran well, when when I left the Interstate and drove slowly the last few miles, the temp gauge went up around 3/4 - it never goes that high, normally. When I was home, I felt the fan motor, and it was hot - I think it has been coming on, but I guess I have not proven that yet. I replaced the original coolant temp sensor (that the computer uses) around 2 years ago, so that should be OK, I think. Last year, I replaced what might have been the original t'stat, and drilled a small hole in it first, in case the head gasket is letting a blast of pressure into the cooling system. Earlier this year, original timing belt & water pump replaced, & fresh coolant at that time. Coolant level is consistent in the expansion tank, seems to not lose any. So this bump in the temp gauge is a big surprise. I checked the engine codes (on-off-on-off-on) and nothing there. My 1st response is that I ordered a new temp gauge sender (Standard #TS-176), to replace what might be the original one. I want to rule that out as a possible reason for the gauge. I will post the results later this week or on the weekend, but if anyone has thoughts, they would be very much appreciated.