The MS3/MS6 tends to give oil a serious beatdown. Most oils will sheer down a grade, either from just the harsh nature of the turbocharged engine, or from excessive fuel dilution (some oils resist this better then others).
Because of this, you really should pick an oil that is more sheer stable to help maintain viscosity. The easiest way to do this is to go with a synthetic oil, that has a small viscosity spread. Like 10w-30 (20 point spread). These oils tend to use less viscosity improvers, and will maintain their viscosity better then an oil with a broad spread (like 0w-40, 40 point spread), which has to use parts of its formulation to try and maintain itself.
Though there isn't enough data to back it up yet, I'm going out on a limb and saying that 10w-30 Penzoil Platnium is going to be my default oil recommendation for these cars. There will be better oils of course (and possibly better grades), but you'll need to do your own UOA's to find this out.
If you're looking for something to try, give 10w-30 PP a try, and get a UOA and see how it does.
For those looking for a thicker oil, I'd probably either search for 0w-30 German Castrol (This is basically a 40 wt oil), or might look into a 15w-40.
