97 Cutlass supreme, use195 or 180° Thermostat for the V6 3.1litre,?
. Heading into Ontario winter season and flushing the system. Read somewhere 190-192 better for computer to fine tuning gas mileage, lol

 

Use the higher temperature thermostat.

 

Ok ,. Is there truth to higher one being more efficient or better for the Performance?

 

Higher temp is more efficient. Lower temp is better for performance IF you also change the fuel map to account for the cooler, denser intake charge. The difference in either case will not be measurable. Run the factory t-stat temp.