Thankfully CAFE penalty abolition took care of that 0W-20 fraud. Chevrolet says if you buy those 3rd generation and later Small Blocks, use 0W-40 oil in the aftermarket applications. Now for real trucks they want the same 0W-40. I own a 3.6L Traverse and use that too.
MY 1976 1 TON USES 20-50 VALVOLINE RACING OIL IN 454 ENGINE.
TOLERATES HIGHER HEAT.