Running hot question

So car runs in upper 3/4 range on gauge around town and middle with heater on 1-2, runs in middle of gauge on freeway with fan off and vent open. I have replaced thermostat, Any ides on what it could be ?

When was the last time you blew the bugs out of the radiator?

Our cars are old. 30+ years of junk accumulates in the right radiator tank and blocks the flow across the horizonal tubes. The tubes themselves get restricted but can be 'rodded' out. I had my right tank removed and it was full to the point that only the top third had coolant circulation. I had back flushed it more than once without getting all the trash out.

Use an infrared thermometer to check the temp at the bottom, middle and top.

If yours is an older brick with an all metal radiator, I'd take it to a shop for cleaning and testing.

The new ones of plastic and aluminum cannot be repaired the same way so must be replaced.

Thanks, for replies I'm going to pull the radiator and get it flushed.