Tim, how come Amsoil isn't on GM's approved list? Even there API certified XL Series? Even some of these small no name companies made it.
Even Pennzoil Platinum made the list, does GM know something about Amsoil not being good for there engines, maybe they see something wrong with Amsoil and they certainly do not need anymore bad publicity or uneccessary recalls because it seems like Amsoil does not meet there standards for some reason.
I hope you are not going to come back with your Amsoil Warranty about motor oil's and them having to prove that Amsoil caused a problem.
Maybe Amsoil motor oil's are just outdated for today's GM Engines and do not offer the right protection.
I know, Amsoil doesn't want to pay for the certification, they'd rather reinvest the money in R&D, LOL. Odd considering how many GM products are on the road.