I have used Mobil 1 5W30 in my vehicles for over 15 years, changing between 5K and 7K miles (on avg, have gone 10K between some changes). I put over 140,000 miles on each of two of these vehicles (86 Honda Accord, 96 Nissan Maxima). Both of these cars were running fine when I traded them in. The Nissan's oil consumption was still negligable (never had to add oil before a change), while on the Honda I would have to add a quart after 3K-5K miles. At the time I felt tha the Honda's oil consumption was due to a change in driving route (I was down shift alot down a steep grade).
I use M1 synthetic for the extended drain intervals. I have the oil changed by the dealer when it is convenient. That is, I will wait until I also need a tire rotation, or new plugs, etc..