Maybe it makes no difference at all, but technically non OEM violates the warranty, not for the oil, but for the additive. You have no idea what materials are used on the new '18+,1-2 Sprag clutch facing or the bonding agents used for the bands. Maybe in your discussion someone might remember the fiasco that occurred when the previous version of Mopar tranny fluid was used in newer Torqueflites and it loosened the adhesive on the bands causing catastrophic failures.
Maybe no damage, but maybe there is, and maybe it even exceeds specs and maybe it doesn't because the aftermarket premix contains the incorrect concentration of additive., but ....so you save a few bucks and have to fight with the dealer and go through arbitration if it craps out. And the Magnuson-Moss Act won't help you when the dealer wins by showing you invalidated the warranty using an unapproved additive.
It all boils down to one question you have to ask yourself......."Would you be pi$$ed if you take your new $50K car for service and the mechanic sticks in some generic oil containing an unknown generic additive instead of the specific AC Delco oil brand and exact concentration of the specified AC Delco additive just to save $10 bucks?" And you can't judge how "dirty" an oil is simply by looking at color especially when you don't have a bottle of the proper OEM oil to compare it against.
Current Chevys -'16 Silverado LT;'18 Malibu LT Redline;'18 Traverse Premier Redline<br /><br />Previous Chevys:16 Malibu LT2 '17 Impala;'16 MalibuLT;'15 Camaro LS;'15 Traverse; '13,'12 and '07 Avalanche LTs; '11 Tahoe LT; '13 &'11 Malibu LTs; '08 Trailblazer;'06 Colorado WT..... Chrysler era.....'80 Citation;'75 Impala;'72 Chevelle;'69 Camaro R/T;'65 Impala SS;'62 Nova