Originally Posted by Modshack

I think you're making it a bit more complicated than it really is.

There is always oil flow through the cooler regardless of temp. When cold it is a limited flow, but the thermo plate remains slightly open to allow this and avoid thermal shock when the 180 point is reached. 180 is the point that the plate opens fully for max flow and cooling.

Popping off one of the AN fittings at the plate allows oil in the cooler to drain by gravity as it is mounted higher on the car

When started up the cooler is immediately filled.

Final oil levels should always be checked and adjusted after filling to approx. levels, running the car to fill the filter and cooler, and allowing oil to drain back to the sump for accurate measurement via the dipstick.