Mobil One. early 80's, with a new car I drove 30k per year. In those days conscientious people changed their oil every 3,000 miles. I wanted to extend that to 6,000. The car did not even break in until 30,000 miles had gone past. It just ran and ran and ran, without skipping a beat. It seemed like the fountain of youth for cars. That car was like two cars, and the money I saved was the downpayment on my first house. It went to 236K before losing an argument with a cow.
It made a believer out of me, but times change. Reading this site has convinced me that a 5k change will absolutely positively be fine. For 95% of us, 7K plus is just fine.
I need to pay more attention to fuel quality. Back then no one paid any attention to that. You just went to whichever station was cheapest by two cents.
By the way, the Ford manual says in so many words that we all need to quit obsessing over OCI and start paying attention to fuel quality, so its not just my imagination.