Since there has been a clear trend from 180 on up to 207+ coolant temperatures think about experimenting there. Since there is good older evidence that 140 - 160 is best for peak high rpm power, those higher coolant temps were adopted to increase fuel economy at lower cruise rpms.
185 thermostats have been the specified rating since at least the 40's. Nothing to do with economy, everything to do with decreased engine wear not to mention oil sludging.
