slant 6 gettin WARM

The bottom line is that the thermostat's job is to keep the engine from running too cold.
The rest of the cooling system is there to make it run as cold as possible.

The two work together to make the engine temp as constant as possible.

Putting a lower temperature thermostat in will only lower the engines temperature if the rest of the system has the capacity to cool it that much.

If your engine is overheating with a 180 thermostat it will overheat with a 160 just as much.