Right now I'm running a 205f and its running warmer then usual so if I switched to a 160f would that help run cooler

 

180 is the lowest I would go.
Some report getting check engine light or a code with the 160.

 

But technically the thermo would open sooner meaning it would run cooler or not

 

All engines are designed to be run at a certain temp. If they do not reach a minimum temp they will not reach peak efficiency. If it is computer controlled it will set codes and may never come out of limp home mode.

 

I just read through your post and I guess the question I would like answered is how much warmer is the truck running and why are you concerned?

 

Around 3/4 to the hot end maybe half way on highways

 

have you checked your rad fluid level?

 

Sounds like you don't actually know what temp the engine is running at due to the use of an idiot gauge which is what my truck has also. Idiot gauges are only good for a reference of what is normal for that gauge/sender combination in that particular engine. Running a colder thermostat may or may not lower the temp that the engine runs at depending on why the engine is running at the temp it does. The thermostat only controls the minimum temp if the thermostat is working properly. After the minimum temp is reached any running temp above the minimum and any overheating is controlled by a lot of other factors but not the thermostat if it is working properly.

 

Did you have any problems with the 205 before? How long did you run it? Whatever thermostat was in my truck slowly started sticking closed more and more over a period of two weeks. I now run a 190 which has done just fine, winter and summer.

 

Its been **** about 2 months now. How can u get an actual degree reading if the gauge is just a ball park figure