[jhv48]

Is your radiator shrouded? Do you have a pusher or puller fan? What temp does the fan come on?

If not shrouded. Shroud it. If the radiator is up to the task, a shroud will maximize it's use. If shrouded, upgrade the fan cfm. Dual fans could also help.

Lastly, why the 160 thermostat? In the winter, you won't give your engine a chance to warm up to normal operating temperature. 180 would seem to be a better fit.