Ive had 2 UOA done on my 2010 Traverse. OLM read 50% and 47% (about 5000 miles on oil)
UOA showed that the oil was ok- but I would not feel confortable letting the oil go another 50%.
UOA have shown MOBIL 1 to get beat up by the DI engines.
Most of the owners who have their oil analyzed-- are no longer letting OLM get past 50%.
Like me- I will change oil at around 50%.
With this dexos 1--- it sounds like they need an oil that will not get beat up by the DI engines.
As for why it beats up oil---
And heres a possible reasonf why DI engines show soot on their tailpipes so soon...
and why quite a few UOA show fuel dilution to be high.
Heres an interesting response from a Pennzoil engineer in regards to the DI engine
"Direct injection gasoline engines are more akin to European light diesel engines. They produce soot and nitrous oxides just like a diesel engine. If they have stratified fuel injection then they need a thicker oil (fuel dilution of the oil on the cylinder wall). Pennzoil Ultra™ Euro 5W-40, with its European light duty diesels qualifications ACEA B4 should be excellent in this application"