Shell Rotella T6. It's marketed as heavy diesel oil, but it meets the exact same specs as mobil 1 full synthetic and just has some extra detergent like diesel oils do.
This oil in OG 9-3 that have the crankcase retrofit kits clean the entire engine very well after a few oil changes getting rid of and preventing any sludge issues. The oil even eliminated some nasty tappet noise due to low oil pressure in my 2002 9-3 after a few seconds when I bought it.