The more I read on oil, the more I think it's a religious thing. There are so many people whining about dexos, when there are other manufacturers that have specific oil specifications. I've been a Mobil 1 user for years and Mobil 1 is dexos approved, so it's a non-factor. Too many people that seem to have a religious belief that if they can't use their precious Amsoil, Royal Purple, Schaeffers, etc., that not driving again is a better solution. My thing is, if Amsoil, Royal Purple, etc., are SO SPECTACULAR, just get dexos approval and be done with it. Other oil makers have done it: Mobil 1 Castrol Pennzoil Kendall Quaker State There are even a bunch of oils that I've never heard of on the licensed list. http://www.gmdexos.com/licensedbrands/dexos1licensedbrands.html For what Amsoil and Royal Purple charge for a quart of oil, they should be on the list. I am in no way religiously tied to Mobil 1 oil. If Mobil 1 was not on the dexos list, I would choose an oil that was. Why is it that other manufacturers can require lubricants that meet a certain specification and it's OK, GM does it and they are bad?