Obviously the 40% was anecdotal based on speaking with 2 different GM mechanics in my town and based on my experience and that of many of my friends. I build hotrods for a living. Currently own 2 Corvettes, a 32 Ford 3 window with a ZZ4 motor, and wife's classic Shelby GT 500, etc. Lifelong Chevy guy. I raced off road trucks years ago. Before I decided to buy the ZR2 I spoke to a local GM service tech who advised me NOT to buy anything with the 6.2 based on his dealership's experience. As due diligence I contacted a second GM employee who basically told me the same thing. I have no idea where you live but here on the east coast these trucks, and as you mentioned Tahoes, Yukons, etc are coming back with failed 6.2's at an alarming rate. So in my opinion, just speaking on the Silverado's, 80K is not an unrealistic number for the entire country. It is still cheaper for GM to repair 80K under warranty rather than recall 200K. I have no info on the rest of the models.
Problem is, they are repairing these 6.2's with the same known defective parts. It appears that if you hire an attorney they will replace the entire motor however according to my local dealer they can't get the 6.2's for 10 or 12 months due to all the replacements. So you pay $75K for a truck that will sit on a dealer lot for 10 months while you make the payments.
My last Silverado 2017 with AFM ate the lifters at less than 10,000 miles. All GM would do is replace one bank and call it a day. I have since been told that a tech bulletin came out recently that allows both banks to be replaced (but again with the defective parts). Now that DFM has 16 defective lifters it greatly increases the chances of failure.
So you ask, why did I go ahead & buy the ZR2 knowing it would fail? I convinced (after paying sticker) my local dealer to extend my powertrain warranty to 200,000 miles and replace the motor when it fails. I just purchased the ZR2 last month and it already has the dreaded death tick and 'service engine' lights.
Second issue. I have gone thru many channels at GM and they all refuse to even discuss the issue. While the local dealerships are well aware, the corporate minions are under a gag order from GM evidently to not discuss. They won't even answer a simple related question. So if there are any real GM mechanics out here that are willing to talk, my question is "if I drive my 6.2 in L9 to keep the DFM from engaging will it extend the life of the motor? Simple question. (I am getting conflicting info from my local guys on this).
I realize the predicament GM is in with the government forcing them to meet mileage guidelines however this DOD garbage is not the answer. GM is screwing all of us over and refusing to admit the truth because it would cost them dearly. I look forward to the current class action lawsuit, but we all know that GM will tie it up in court for years rather than admit wrongdoing.
Do yourself a favor and go to YouTube. There are dozens of postings on this.
I've read the opposite regarding DFM vs AFM and the failure likelihood. My understanding is that the programmed deactivation scenarios on DFM make it less likely for failure, since the same cylinders are not shutting off every time as they would with AFM.
As you stated, 40% is anecdotal, but you also believe that number based on your own personal experiences and as well as those of owners and mechanics you've spoken with. FWIW, I've watched several explainers on YouTube, and scoured the GM forums for Tahoe, Yukon, and Silverado to get a feel for how common the complaint is. It seems to be even more prevalent on Yukon than on Silverado, but there's a fair amount pointing to the fuel pump as a common failure point.
All of that considered, it's certainly not an insignificant issue, and it seems to happen early in the life of the engine, which makes it all the worse for new owners who spend the most $ as the first buyer.
I'm not convinced however, that the occurrence rate is anywhere near 40%. If it were, the ZR2 forum would be plagued by postings about it, since that is the only engine offering available in our trucks, and this being a flagship trim level and in its first generation, postings here should be more active and timely than some of the other forums. I've seen maybe 5 or 6 confirmed occurrences?
It would be helpful to know from an administrator how many users there are, how many are confirmed owners, and how many are active on a weekly basis, to put the number of reports into perspective to the population of owners.
From my experience here, on the Jeep Wrangler TJ and 392 forums, as well as the Ram TRX forums, enthusiast auto forums are much more active than commuter and kid-hauler forums, but all auto forums share the characteristic of being riddled with postings about mechanical issues and problems. My theory is that the forums are a reasonable sample size to identify common issues, but small and highly concentrated by owner-types, enough to make those issues appear disproportionately more common than they are. YT content creators just piggyback on those trends, or speak from personal experiences.
Starting a new thread to track this issue specifically for the Silverado ZR2. Invite those who have confirmed cases of lifter failures to post there. Evidence in the form of repair invoices and receipts would be helpful too, as well as VIN, so that we can paint a more accurate picture of root cause and identify any commonalities.