I took a sample from my 2019 CTS-V with just under 5K miles. I changed the factory fill at 1,890 miles and went with the new 2019 Corvette spec Mobil 1 0W40 ESP. This is NOT the M1 0W-40 Euro formula. So far looks good after 3K miles with a TBN at 5.1, so will run it for at least 5K miles between change intervals. This oil seems to be good according to Blackstone labs. M1 developed it specifically for the Corvette LT1/LT4/LT5 engines.