The new corvette spec 0 w 40
as said above the 30 or 40 or x depends on bearing clearances
no reason to run a 5W or 10 W anymore most mfg have service bulletins saying that 0W is OK and is better for the reason stated above
The O'riley and other house oils may be made by Valvoline but are they same? check the data sheets
not pushing mobil 1 but do not see a corvette approved oil from Valvoline or Penzoil