Good point was made on the Marketing agreements between various manufacturers. In the Owners Manual for the Corvette, it mentions that all
synthetic oils do not meet the standard of GM 4718M, but Mobil 1 does.
Might it be that only Mobil 1 meets the standard ?
The
oil filler cap states to use Mobil 1. The price per quart at Wal-Mart is $3.97 X 6.5 quarts = $25.80 for the
oil change.