Glenn Brasch
KRYN Tucson, Arizona
2013 RV-9A
Medevac helicopter pilot (Ret)
EAA member since 1980
Owner, "Airport Courtesy Cars" website.
www.airportcourtesycars.com
Volunteer Mentor www.SoAZTeenAviation.org
It might drop below dew point in the evening from heat radiation out to the night sky if parked outside or perhaps in a hangar with a metal roof.
Even in dry country, if you run it only a few minutes the moist combustion gas gets past the rings and into the crankcase. I think it was Piper that tested periodic short engine runs for storage and found it to be worse than no periodic runs at all. The oil needs to get hot.
The upper surface of any tank tends to collect dew. My tractor diesel tank gets wet on the inside of the fuel cap.
I suppose the same happens in a crankcase. I wouldn't worry about it. I do nothing here just 400 feet from the pacific coast.