Delvac 1 5W40 "year round" with oil anylization every 5,000 to 7,500 miles
may allow you to run as far as 10,000 miles between oil changes.

Mobil ( I can't print Exxon Mobil without getting the whim whams about
Alaskan estuaries) will soon come out with a drop in style synthetic oil
filter that filters down to five (5) microns.