Mobil 1 is good oil but not great.
It's a notch below of what are considered to be the best oils out there - RedLine, Amsoil and Schaeffer which will keep your engine cleaner and show lower wear number in oil analysis.
And they are not that expensive considering that you can
safely prolong you oil change intervals up to 12-15K miles.
I buy RedLine for $7.00/qt
here. Keeps my engine clean as a whistle at 55K miles.
Royal Purple? Nah... Lots of gimmicky marketing.