On my daily I change oil and filter every 5k miles even if the car says it can go another 10k. On the Speedster I changed it every 3k or so since I figure the oil is carrying a bigger part of the load in an air-cooled car. I had a full-flow system with external cooler and filter. Maybe it's not necessary, but it's cheap insurance. I would check and adjust valves if necessary at the same time.
On the Coupe I haven't changed the oil yet at only ~300 miles open a water-cooled Subaru. I expect that I'll stick to a 5k schedule.