I used Mobil-1 in my Lincoln Mark VII 5.0 HO for ten years ending at 250K miles when the rest of the car needed $$. I pulled the engine last month with plans to overhaul it and put in my ski boat. When I opened the engine it was extremely clean. Now I think I will keep it intact, replacing simple seals and pass on the overhaul. It was only using about 1 quart of oil [which included minor leaks] every 3000 miles and it did not smoke at all. My oil change frequency was about every 7000 miles with a new filter midway.
