storing an RV

Stabilizer only helps for so long. Having said that I've left a MH sit for more than a year. First tank will not give you good mileage but should improve with fresh gas. If you want to have it serviced wait until just before you're ready to go. Don't start it, don't drive it unless you're going to drive it enough to really warm it up, engine, exhaust and trans. The worst thing for an engine is to start it and not drive it enough to get it hot to dry things out. A by-product of exhaust is condensation. Do exercise the generator every month or two under a load, A/C, heat pumps or etc. The generator brushes and contacts can corrode if not exercised with a load. If they do corrode your generator may be useless until it's taken apart and the corrosion removed.