ok I feel like a dummy now, but I wonder why they offer both other temps in thermos if there is no real purpose? My other experience with them was a decade ago or so with my v8 Camaro and had I higher hp rating than stock and had a lil better performance with the 160 thermo rather than the 180.
Don’t install any thermostat other than 195F. It can only damage the engine, cats etc. The idea is that the engine is designed to work at 195F to 210F, and the thermostat is supposed to make sure that temperature never goes under 195F.
You will get check engine light if the PCM detects that the engine cannot heat up to proper temperature.
There is a little bit of science behind this thermostat thing.
The thermostat is responsible for setting minimal steady state operation temperature.
If you put 160F degree thermostat, then it means that your engine will run at 160F degree if the weather is cold. Let’s say you put 160F in Alaska, your engine most likely will never run above 160F. That is the point of minimum operational temperature.
If you engine succeeds to reach 210F, this means that whether you put 160F thermostat, or even if you completely remove it, you still be at 210F degrees.
Maximum operating temperature is defined by quality of radiator, fan, fan clutch, water pump and the coolant, airflow obstructions and ambient air temperature. 215F is not too high temperature for 4.0. Ideally it should be between 195 and 210, but if you idle for a while with AC on, you will reach 225F and even 235F if any of the cooling components are not in ideal state.
