There are some very good WRX uoa's on Amsoil HDD 3000 over at bitog. FWIW, here's another opinion from someone very knowledgable about Amsoil. He pretty much agrees with me about not running the girly man oils.
I think somebody mixed up the samples. That looks exactly like the 5w-30, XL Series oil in terms of specific additive chemistry. I'd expect the XL to shear down in a turbo application.
Why would you use the very low SAPS oil in a Subie turbo, when Amsoil has many better products available??? The DEO 5w-40 is now an API licensed, CJ-4/SN oil. That's what folks should be using in these turbos. Yes, I know that 5w-40 is no longer recommended. But that's just an attempt to maximize fuel efficiency....