I think there are 2 schools of thought on periodic starting of a car that has been suitably prepped for a long winter sleep (necessary here in MI, if the car hasn't seen winter ravages).... Any thoughts on the downside of an occasional 15-20 minute start and idle as opposed to leaving it rest under the cover with a float charger attached? I have concerns of leaving residual pipe and muffler moisture and maybe corrosion. It was parked hot. Comments?