While I don't intend to follow the manufacturer's recommendation of an oil change at 2 yrs or 20K miles, I'm not going as far as to change it every 5K miles. We have to make our contribution Mother Earth and use her resources wisely. I was planning to service the car at 12 months. My comment about oil consumption was based on the 911's propensity to consume oil. I recall 1qt every 600 miles being "normal" for the older 911s.
The only vehicle that I changed oil frequently was my motorcycle, 1 ga of full synthetic every other month; but it saw regular use on the track.
Air-cooled; don't get me started. One of my absolute favorite sounds is the wail of an air-cooled 911.
