You would be better off connecting a battery charger to the engine or chassis batteries than you would be starting a diesel engine. The engine would not be run hard enough during an idle process and can actually harm the engine compared to doing nothing. Just park the coach, shut it down and leave it that way until you are ready to travel again. You can call any engine manufacturer you like and you will get the same advice. The oil should be changed once a year even if you don't make the manufacturers recommended mileage and changing it just before you park for the extended Winter hibernation is a good idea.