I just noticed today that when I first drive my 92 4dr the temp gauge starts cold then when it starts warming up it will go almost to the "Hot" line and then settles back down to a little off center, toward hot, and stays there the rest of the time.   Is this normal or do I have a thermostat issue?    Should I even worry about it since it runs in the acceptable range?

Im new to the sammys but i know on my old chevy i had this issue and it can be a number of issues. i would check your coolant level to make sure it is full(air pockets can develop), check for leaks, also moisture on your sending unit could cause this. I ended up replacing my thermostat and it fixed my issue. this is a cheap fix

change your thermostat

Remember that the temp senders are not liniear, they are stepped. The sender can be off slightly in calibration and merely reads high enough for the temp gauge to rise to the next segment. Use an actual gauge to determine the real temp(even a IR gun will work) to verify it is out of spec before you go replacing parts.

The gauge sender is a negative coefficent thermistor - whilst it is not linear, it is certainly not stepped - the curve above is taken from the factory service manual.

The problem described is more likely to be thermostat or circulation related rather than the gauge calibration.

The gauge sender is a negative coefficent thermistor - whilst it is not linear, it is certainly not stepped - the curve above is taken from the factory service manual.

The problem described is more likely to be thermostat or circulation related rather than the gauge calibration.

  maybe I could/should have worded that better, the sender is certainly not stepped as you point out. but how I understand the gauge to work is that it is a dampened/stepped and moves the needle as those thresholds are reached by the output of the sender. Not saying it is definetly the issue, but i have seen a sender changed and the gauge shows a different temp/pattern.

I'm not sure we're thinking along the same lines but what ever it is you have in mind, if it involves "steps" then I don't think it's applicable - this is a purely analogue system - it does have some form of damping to prevent rapid needle movement from confusing the operator, but I believe that is thermal - it has been a long time since I opened a gauge, but the last time I did there was a voice coil movement in there - granted newer models do have stepper motor gauges, but these cars aren't that new.

Yes - you can change the sender or the gauge and see different readings - it's not a precisely calibrated system.