Purge with Thermostasis unit

It does NOT "Isolate" the Cooler.
the thermostat partially bypasses the Cooler.
The Oil flow will split and fill the cooler and all the hoses.
Just purge as you normally would.
On the first start, the pressure might fluctuate momentarily but should stabilize above 30psi(2bar) within 5-10 seconds.

OK, Thanks Bill

When I installed the Thermostasis unit I pre filled the oil lines the cooler and unit as much as I could with oil. I purged and cranked the engine with ignition modules off and got oil pressure almost immediately. No Issues.

I did not have any problem purging with the Thermostasis installed, once I applied shop air.

Without shop air, though, I could not get pressure.