i have just got a good spare engine, but will not be using it for a while so it is going to be sitting on a shelf for a bit, it is oil tight has a good cooler attached etc, now the question is would it be best to keep it full of oil while storing or to drain it out?
The parts you should worry about are the ones that don't have oil on them, cylinders and valves....etc.
You should fog the motor before storage. That will keep it from rusting up on you.