Don't know about your 2007, but for our 2003 E450 Ford recommends their Motorcraft 5W-20 semi synthetic oil. The filter is the Motorcraft 820S. Both available at Walmart.
I change the oil and filter every 5,000 miles, although I have gone over that number somewhat a few times on long trips.
During long periods between trips (mainly Winter) we take a drive to a mall about 20 miles away to give the engine, drive train, brakes and other moving parts some "exercise". IMO regular exercise is good preventive maintenance.