Never used Amsoil , like any other oil , many swear by it , and , many swear at it .
Lots here use it and are happy with it ..
I have also used Mobil 1 15-50 and the Mobil 1 V Twin 20-50 . I had one bad oil analysis ( I do it every oil change ) and switched brands ..
I have used the Harley Syn3 , which IS NOT a full synthetic , and I have a used oil analysis that shows it is a very good oil ...
I am an extended drain guy and pay a few more bucks for Redline 20-60 and their shock proof in the trans .. I use their primary oil as well , but that's one you don't have to be so picky about .. I cant get it locally , but I mail order it before it is needed ..
Use a good brand name synthetic and change your oil regularly and all will be well in your world ..
There are very few oil related engine failures directly attributed to the oil , unless it isn't changed ..
JtB