I have used mobile one in my cars exclusively for 15 years now. Unlike the earlier vehicles, these have not develop engine wear problems. The car I bought well used with 160k miles on it sucked enough mobile one past the guides to puff on start up but it never got worse. I gave it away with 230K running strong.
The Taurus we have has 80K miles using mobile one and burns insignificant oil between changes which I do at 3K intervals. In my older beater truck, I don't think I could pour mobile one in fast enough to keep it full. At 100K that vehicle suffered a stuck lifter and was heavily varnished inside. At 80K miles it was always down 2-3 quarts at 3K miles using dino oil. That was fed dino oil since new.
On a new engine, I would break it in with dino for the rings to seat. Then I would use mobile one from then on. I don't believe there is harm switching from one to the other and back, but I see no reason to run dino oil after the rings have set.
