Paul, It sounds like you are covered. I would recommend a synthetic oil. When I got my bike I changed the oil at 1000 miles. The original owner had done a change at around 400 miles. The oil that came out was in terrible condition. I used a 10w-40 full synthetic for the change. I changed it again at 3000 miles. The oil was dirty, but it was as slick as the new oil I was putting into the bike.
Air cooled engines are really hard on oil. I used to find my old beetle destroyed the oil between changes. With an air-cooled engine the oil has to absorb and dissipate that heat elsewhere in the engine. The Synthetic oil doesn't break down as easily when heated.
Hope you enjoy the ride!