Car temperature gauge very erratic

In the last month or so I've noticed, mostly on the highway, that the temperature gauge is fluctuating quite a bit. It's almost is never right in the middle between between hot and cold where it should be. It's usually just slightly more that the cold reading. If I turn my heater on though I am getting plenty on warm air into the car.

Low coolant level ? Water pump ?

Welcome 99 Proper coolant level would be the first thing you should check. Maybe your thermostat is stuck open.

Is coolant level different than anti-freeze level ? Feel free to laugh :)

Welcome 99 Proper coolant level would be the first thing you should check. Maybe your thermostat is stuck open.

Engine Coolant should be a 50/50 mix of anti-freeze and water. Anti-freeze level could be measured as the level of freeze protection that the coolant provides according to the mixture. I think in the terms you are asking, no there are not two different levels to check.