Another thing to think about with an
oil cooler and thermostat is adding a check valve into the return line from the cooler. The reason for this is to reduce the chance of splitting the cooler with cold
oil under high pressure being fed back from the motor on start up.
The galleries of the
oil cooler can be quite restrictive to cold oil due to it's higher viscosity. When the engine is cold and the thermostat is closed it is only diverting flow from the engine away from the cooler. The other side of the cooler is still connected to the oil gallery where it feeds oil back to the motor. This is still under pressure and cold engine oil pressures can also be quite high (we have pressure but not flow if that makes sense).
A check valve in this line from the cooler to the engine stops the pressure reaching the cooler until the thermostat opens and oil starts flowing through it.
I'm also set up with an accusump so that when you turn the key it pre-oils the motor. The check valve also helps ensure the oil flows from it to the motor and not towards the cooler. I've since changed the valve in this pic for a full flow swing gate style check valve.
Cheers