OMG, please do not start with Amsoil... Their filters are no prize, their oil not special, their marketing misleading and their science questionable.
Before you point me to a thousand web sites, find me a single part in an engine that looks anything like this:
Their much touted 4 ball test... or even a single point contact wear location.
And don't get me started with the spinning wheel vs. bearing on a lever test.
I am not saying their products are bad, just that they are nothing special and certainly not what they make them out to be. They remind me of a cult and I won't drink the Kool-aid.