From what I can tell, the main difference between dexos1 and dexos2, aside from the oil weight, is that dexos2 requires medium to low levels of SAPS. SAPS are sulfated ash, phosphorus and sulfur which are detrimental to diesel catalytic converters.
However, the standard oil calls for dexos1 which can be full SAPS, which makes me ask how the car is affected by this figure. Most Camaros will see over 100k miles with nothing but dexos1. The only two reasons I can see dexos2 being specified are:
1) The engine needs the extra protection of a 40 weight oil, and dexos2 is the only GM certification available for that.
2) At high load of track events, the emissions equipment is more affected by SAPS. However this doesn't make sense as they also recommend Mobil 1 15W50 which is full SAPS.
Some discussion on the subject:
https://bobistheoilguy.com/forums/ub...opics/4224569/