Graham Bell wrote a book...
Modern Engine Tuning.
He has a chapter on oils. He has done tests on “ mule engines” he uses for comparison tests. He concludes that Mobil 1 comes out best. He measures engine parts before and after for wear, monitors cooling, mpg etc as part of his tests.
I use the Mobil 2000. It has a good additive mix for the Rover V8 ( zinc compound to protect the tappets/valves.).
