FWIW my car seems to "loose" mobil one (not burning, maybe evaporating?) So I have been using Rotella T6 5w40 with great results. Its a diesel oil and has lots of detergents in it, I have noticed cleaner cams in the couple times I've had the valve cover off. Also, it seems more quiet at startup especially in the morning.
Member #2 of the Boston Green Mafia BMW-CCA #457574
1995 BG M3 2000 TiAg 4.4l X5
-I do the things today that others won't do, so I will have the things tomorrow that other won't have....