Todd - the dexos specification wasn’t applicable to anything before the 2011 model year. The Acadia/Travers/Enclave people have been monitoring the oil and have found that they’re hard on oil, but I don’t know if that’s the case for just this engine or other DI engines.
No one told me anything about using different oil. If I had taken it to, well, we’ll just call the dealer “B”, they woudl have used whatever oil that they usually use. DJPyro and Justin seem to work for more informed places.
I have trust issues just like you.