Ahh, all great points. Me being the busy body I am, I once neglected to change the oil on my Jeep Cherokee, for 23,000 miles. It was still working great when I sold it with 176K milles. My current 4x4 is a toyota tacoma 4cyl. The dealer had a great incentive, free oil changes for life. After the warranty period expired they started scheduling my oil changes to every 10K miles. just something to think about. My current testing of the shell tier 1 gas has not resulted in any significant mpg gains, certainly not worth the .05 per gallon extra cost.
If a synthetic oil lasted twice as long then it would be a benefit because it would save me time from going for service as often. Kind of like to toll reorganization here in jersey.