People talk about Amsoil not having any manufacturer approvals BUT... that is not true. Pablo mentions AFL. AFL has MB 229.51 and Porche A40 approvals. EFL which is Full SAPS has MB-Approval 229.5, Porsche A40 and VW 502.00, 505.00.
Personally, if would trust it with a Porsche approval. Some people will put Amsoil down because they don't like how they market their product. Some people will put it down because they had a bad experience ONCE which I'm not sure was even proven to be an oil problem. Some people will only use Amsoil for other reasons.
Full disclosure, I use Amsoil. BUT I have also used M1, Castrol, Rotella T6 and Total and I want to try Redline. I am moving away from Amsoil not because I have an issue but due to cost, warranty and mechanical problems which have nothing to do with Amsoil (blown turbo). However, I may be going back to Amsoil for my wife's car since she is out of warranty and we are doing extended changes.
Feel free to use Amsoil and not worry. Just choose your brew. If you don't like it after 1 or 2 changes then move on to something else.