In the grand scheme of things, oil is cheap. I go 7500 miles on both a 4cy and 8cyl with Mobil 1 and a good filter. Many new vehicles are coming with 10,000 mile intervals now. My last BMW, Toyota, and Volvo all had 10K interval recommended from the factory. Don't go over 10K or one year and you will be fine.
That being said, if you know you are getting contaminants like gas blow by then change more often.
Good post.
