[waterman]

"For the ZL1 1LE, 15W-50 is the required track oil due to the increased lateral acceleration capability of the vehicle. It has enough of a grip capacity increase above all the other models that the added protection from 15W-50 is needed. The thicker 50 weight viscosity helps with oil pan drawdown when the oil gets hot on the track and reduces risk of pressure dropouts. For the ZL1, 15w-50 will add protection but is not required, as the 0w-40 was tested and provides adequate protection in a track environment.

Since Mobil 1 15w50 is not Dexos-certified, it is not recommended for long-term street driving use. Follow the Owner’s Manual and switch back to the 0W-40 Dexos-certified oil after your track session is over and you are back to street use.
With regard to the new Mobil 1 0W-40 ESP Dexos 2 oil, it is an acceptable oil for both the street and track, for the SS, SS 1LE, and the ZL1 due to having less aeration. However, it is not recommended for tracking your ZL1 1LE."

Per Al Oppenheiser.

Valvoline MST (Dexos) is fine for street application.