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What we see are several things. One, if LS3, the valley cover baffle may not have been bonded properly during assembly and sucks oil right in around the edges. TSB on this so warranty should cover.
If L99, then driverside valve cover baffle as well, but that is rare.
Most though come down to driving easy (babying) during break-in and that does not allow the rings to properly seat due to the factory oil fill being M1. You only get that first few hundred miles to accomplish proper seating, or ring/cylinder wall "wear in".(TSB's on this as well if you search) If babied, odds are the rings never seated during this brief window and once the cylinder wall glaze sets in, the rings cannot seat further so excess blow-by and oil consumption are the result. We if determined that the oil consumption is excessive (more than 1 qt every 1000 miles depending on country your in) then we tear down and install new rings. Personally I always cut the glaze and re-hone, but GM will not reimburse for this as so many techs do not understand how to do so properly and if cut to deep, then it is another issue. (Only takes a few minutes so I do it to ensure good seating) You as a consumer, get a totally different guide to engine break-in than we as techs get so this is among the #1 issues we see under warranty (and timing chain stretch on the 3.0 and 3.6L V6's).
We are NOT to discuss this with customers though and are instructed to only say "We haven't been made aware of any issues" so keep on them politely. There is NO reason these engines, or any new engines should consume oil like this.
Also, the AFM allows more oil mist inside the crankcase and that contributes as well.
Do a search here for the APEX thread on engine break-in to see the instruction page that comes with every replacement/crate engine to see how to properly break the engine in and avoid this in the future. I have yet to see one use oil after breaking in properly. Good luck!!
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