Let me first say everything I read on the WWW is taken under advisement. I like Amsoil, but they do spend a lot of money promoting their product, and a lot of their claims I also take under advisement, with an open mind.
Here is the Amsoil / Toyota thread. As you can see people attacked and defended Amsoil, casting some doubt.
This thread is interesting showing Fram as one of the best filters for Flow. We know the deal with Fram. Truth is after reading through most of the the thread it seemed, at least to me that they never perfected the test. But still a lot of time and effort went into it.