I was in the local Chevy dealership today and they had stacked around the waiting room many of the 1 litre bottles of the AC Delco dexos1 synthetic blend, interspersed with Castrol SLX Professional. I snapped a pic of the front and back of the Delco bottle. I asked about the price and no one knew as it wasn't yet in the system.
However the parts guy encouraged me to instead buy the Castrol SLX Professional 4718.
I pointed out to him that for sure this Castrol oil was a quality oil but not dexos1 certified and so techically could not be used in MYs 2011 and beyond. He disputed this claim.
[Did we always know that any dexos1 oil "superseded" the 4718M rating? See below:]
However the parts guy encouraged me to instead buy the Castrol SLX Professional 4718.
I pointed out to him that for sure this Castrol oil was a quality oil but not dexos1 certified and so techically could not be used in MYs 2011 and beyond. He disputed this claim.
[Did we always know that any dexos1 oil "superseded" the 4718M rating? See below:]
Last edited: