Yet you fail to address why GM on October 2013 (under Bulletin 13314) Service update for Inventory vehicles for the L83(5.3L) and LV3(4.3L) engines refers to part number 19259487 (0w-20 DEXOS) and for our neighbors 19259784 (also 0w-20) as the replacement oil? If this bulletin is not fact based, then what is?
Somebody missed the difference. That's the answer. Bulletins are updated every day to correct errors, omissions, add info, and remove info. Hang out around GM service info for even the shortest amount of time and you'll see it changes pretty regularly.
#13314 is a Service Update campaign. In this case, it's only for certain vehicles in dealer inventory that were identified by IVH.
It affected all of 42 trucks.
By the time somebody noticed only one oil p/n was on the parts list (if they ever did notice), all 42 trucks had been fixed and it didn't matter anymore.
Since we're playing the "fail to address" game: Care to address why there is a media photo of the 2014 engine with a 5w30 cap? Care to address why the New Model Features call out 5w30 for the 4.3L? Care to address why you can't seem to find a 2014 owner's manual that specs 0w20 for the 4.3L?
Finding an owner's manual shouldn't be difficult. They printed nearly a million of them to go in the glove boxes of every Silverado and Sierra built in 2014.
I couldn't care less about your thoughts on 0w20, but if you're going to lie and attribute part failure because you mis-remembered or "came to find out about" an oil spec that simply doesn't exist, I'm going to "bloviate" about it.