Radiator

[Lonewolf3165]

I don't think the thermostat opens and closes as you drive. That would be like the furnace control in your home. Instead it is a "proportional controller", which reaches a steady-state operating condition, i.e. partially open and not cycling. I think 1968FormulaS340 is correct. If you are over-heating with a 180 F thermostat, your thermostat is already fully open, i.e. beyond the proportional control range or "control response pegged out". A 160 F thermostat would also be full open there, so where is the benefit? The downside would be that a 160 F thermostat could make your engine run too cool in the winter, with poorer mileage, more emissions, and more cylinder wear. Poorer temperature control is why air-cooled engines like old VW's need a rebuild more often than liquid-cooled.

Run a vehicle with(& this is key to what I'm saying) an adequate cooling system capacity, in 50* or less weather especially on a damp day & it should return it closer to the opening temp. It may not drop to 160* but it would be lower than 180*t-stat. The other thing to consider it the thermostat doesn't open or close fully all at once. It opens at a varying amount depending on temperature & how it's calibrated. As the system cools down closer to the t-stats temp rating it will actually start to close some or may even close completely then reopen as temperature increases again. If you have ever driven a car with a t-stat that's stuck open the temp is considerably lower than normal operating temp. Even after warm up.
If you read my earlier post I said it probably wouldn't help matters in this case. If the t-stat isn't the problem it won't make a difference at all by replacing it. But in other cases you can regulate the operating temperature of the engine with a lower rated t-stat. I agree that problems of overheating- assuming a 180* t-stat is operating correctly- will not be cured by installing a lower temp t-stat. I was referring to another member's post here that implied running a cooler thermostat won't do anything to reduce temperatures(in a working system) & that's simply not true.

 

[1968FormulaS340]

Run a vehicle with(& this is key to what I'm saying) an adequate cooling system capacity, in 50* or less weather especially on a damp day & it should return it closer to the opening temp. It may not drop to 160* but it would be lower than 180*t-stat. The other thing to consider it the thermostat doesn't open or close fully all at once. It opens at a varying amount depending on temperature & how it's calibrated. As the system cools down closer to the t-stats temp rating it will actually start to close some or may even close completely then reopen as temperature increases again. If you have ever driven a car with a t-stat that's stuck open the temp is considerably lower than normal operating temp. Even after warm up.
If you read my earlier post I said it probably wouldn't help matters in this case. If the t-stat isn't the problem it won't make a difference at all by replacing it. But in other cases you can regulate the operating temperature of the engine with a lower rated t-stat. I agree that problems of overheating- assuming a 180* t-stat is operating correctly- will not be cured by installing a lower temp t-stat. I was referring to another member's post here that implied running a cooler thermostat won't do anything to reduce temperatures(in a working system) & that's simply not true.

Yes, the thermostat controls the minimum operating temp. None of us are arguing that point.

The point I was making is that if your car is running 215 on the highway or idles 215, both a 160 and 180 would be wide open.