well to keep it from happening is tuff if you keep it outside , if you can keep it under cover as a roofed building not under a tarp will be best. these systems breathe so the climate that you are in determines how much possible consendsation you might possibley get. I would get the cheapest oil and filter that is suggested for use in your machine empty what you can ,refill and be prepared after a few hours of running, to do it again. and look and see if you have made progress on what you see, and possibly do it again. I do not know how tuff those machines are to purge the air out of so that is something you will have to weigh out if you remove all the oil.