I wonder why no one complained about Dexron and Dexcool or Mercon for Ford, same thing right?
Right or wrong GM will claim Dexos just a spec and nothing more. I haven't decided yet if its a good thing or not, both points of view have valid points.
Actually, dexos is not simply a spec. Part of dexos certification is a $0.36 per gallon premium payed by the oil company to GM. So if Mobil sells one million gallons of dexos certified oil a year, $360,000 goes directly to GM.