NS Oscar II should I drain the boiler before storage? I' have a Nuova Simonelli Oscar II machine for events. There is considerable time between those events and I was wondering if I should drain the boiler before storage.

The usual storage time is about 6 months or longer.

Or what are the possible issues that may raise from draining / not draining the boiler.

Thanks
The Oscar 1 has a brass plug that can be removed with a wrench. You can then pick the machine up and tip it over a drain. Some water might remain in the heat exchanger and tubes, but that will get almost all water out. I don't know whether the boiler design on the Oscar 2 is the same, but it wouldn't be surprising. 

If there is any possibility of storage temperatures going below freezing, you must drain it. I would drain the machine regardless.