[oil pan 4]

The 2 way system I described using the GM style "heater" and a straight up Air to oil cooler would need 2 thermostats or a thermostat and thermal switch.
My normally open and normally closed solenoid valve was just a fail safe, could be done with 2 normally closed or 2 normally open switchs.
Actually 2 normally open solenoids might be better.
If the transmission has a lockup torque converter then it will need the "heater" most of the time during the cooler months.

In another post on diesel place I installed an air to engine oil cooler. But I don't want the air/oil cooler flowing at all during winter so I installed a manual ball valve to close off the A/O cooler completely, then for during summer I installed a normally open solenoid valve in line with the ball valve to close off cooler flow during the summer, until the engine warmed up.
I used a normally open valve for 2 reasons, one so if the electrical system failed, it would fail open, the better condition to be in when its hot out, the second reason is when the manual ball valve is opened for summer time use the solenoid valve will need to be open most of the time anyways and that will save power and keeping the valve "off" most of the time should help it last longer.
I left the function of the factory engine oil cooler inside the radiator alone, it flows all the time, the A/O cooler is just there to help it out.