Understand this 0W40 is speced for the Corvette and the Camero with the same basic engine. I think the Camero lists 5W30 if 0W40 is not available. The LV3 4.3l V8 with AFM specs 5W30 engine oil. Understand 0W20 was never spec'ed because these engines needed it, it was spec'ed for these vehicles and almost everything the early 2010's on due to CAFE requirements.
So the 0W20, 5W30 or 0W40 is not going to cause problems.
The problem with 0W20 is fuel dilution thins it out to probably a 0W10 or lower depending on the situation. The L87 6.2l was recalled because either GM found out that the clearances were too great in the engine for some reason or they expected premature wear made the bearing clearances slightly larger or they have finally come to the realization that 0W20 engine oil that is fuel diluted and under great stress as not holding an oil wedge to properly distribute oil around the journals and have a thick enough oil film to protect the engine.
So does the Recall with swapping out 0W40 for 0W20 solve or correct anything, probably not. It may just keep some of these motors alive that have not seized up yet. Might give more of a safety margin for fuel diluted oil. May help if the engineers figured out the oil clearances at time of assembly were larger than anticipated.
I had oil analysis done on my 3 oil drains so for. 544 miles, 3,388 miles and 5,923 miles.
The common denominator was between 0.5% and 1.0% fuel in the oil. On the surface everyone would say, that's fine, that's normal, not a big deal. But you need to understand the big picture. Most of my driving is starting the engine and drive between 2-6 hours straight. If I do any town driving, where I live and where I go, I usually drive at least 30-45 minutes round trip without much of a stopping time. Pretty much ideal driving conditions. Then take the low mile oil change intervals of between 544 and 2,940 miles. Extrapolate out a bit, assume 7,500 OCI then I would likely be in range of 2.5% fuel contamination. AND this is under about as ideal driving conditions as you could expect. What would the fuel percentage be in the oil with 10-20 starts a days, short drives, Auto Stop/Start functioning, DFM fully functional?? Who knows, but 0W20 at the end of its life would probably not be a very good lubricant. It would be nice to see an oil analysis on a few of these 6.2l with 7,500 mile oil changes that do not operate under ideal circumstances to see what level of fuel is in he oil.
Anyway I expect that the "Recall" may be still be getting tweaks with exact wording. At last check the NHTSA has not published the "official" Recall document. Maybe GM is still "Negotiating" with NHTSA about what is the correct solution. NHTSA does not want to see any more vehicles have their engines seize at 60-75 MPH, they may want GM to replace engines, but GM will push back with what they see as a far cheaper and easier solution.
We shall see how all this pans out in the next week or so.
