Engine had to have new camshaft and lifters at cost of over $5k mostly covered by extended warranty. Dealer had vehicle for over 60 days. Based upon my research the lifter failure is a none issue by GM. The 8 cylinder to 4 cylinder mode is causing issue and GM will not fix the issue because it is too costly for the company. If you have a vehicle with this engine feature it's just a matter of time before it fails.

The truck is currently at the dealership, and in the process of tearing the engine apart to find the problem. I think it will require a new set of lifters or a cam or even a new engine....

Update from Mar 16, 2023: Still waiting for GM to supply the lifter manifold so repairs can get under way, after a week and a half with no transportation, I'm getting impatient. The Dealership has been very nice to work with, too bad the parts are so scarce from GM...

Really sad that we as Americans would sell a weak motor and compromise our reputation.

8 spd transmission has been a problem. Clunky, TOrque converter shutter, paint peeling on my roof just above the windshield, maybe like 8-10" dia. paint just blowing off. Now the lifter noise clacking with the engine. It's been the worst vehicle I have ever owned. They need to take care of their loyal customers or the loyal will go elsewhere for a new truck.