Ok, so I finally got a straight answer. I spoke to the guy at the Chevy dealership, and he knew it was me again
and told me that it definitely will take 5W30 and I won't get more of a straight answer than from him because he is reading from GMs program. I said okay well tell me who put on my oil cap and published my owners manual. He said okay, just to be sure, i'll go to our service
side, instead of the parts
side, and see exactly how it tells the service guys to change your oil. He came back on the line many minutes later, with an official GM document (which I later went and picked up) and read to me from the document directly that GM factory filled the 2013 Cadillac ATS, the 2013 Chevrolet Malibu, and the 2013 Chevrolet Spark with Dexos1 certified 5W20 oil and to NEVER use anything other than 5W20 oil.
Also, that Dexos1 5W20 is in short supply due to a manufacturer shortage, so if Dexos1 5W20 cannot be found, then any synthetic 5W20 with an API starburst may be substituted for it.
I also found at my local parts store that Mobil1 5W30 is Dexos1 certified but th 5W20 isn't. But! Valvoline SynPower 5W20 is! I checked out also Castrol Edge 5W20, Royal Purple 5W20, and Penzoil Platinum 5W20. None of them are Dexos1 certified. Many of those makes 5W30s are Dexos1 cert, but not the 5W20. I personally don't prefer Valvoline, but looks like thats what I'm going with!
So I FINALLY got the answer I needed!