Hi Dan.
by turning the engine over by hand to drain the oil when the valves open.
Although it has been a lot time since I have flown an radial engined aircraft, the DC-3, we were told not to pull the prop through by hand as this could cause internal engine damage. It was recommended to use the starter because the clutch will slip before enough torque is applied to damage the engine.
We need to ask
pigboat, I will happily accept his answer on this subject.
I could be wrong and it would not take much for me to change my opinion.
Take care, C-P