I think Amsoil is a great product but I don't think it's so much better that I would give up the availability and convenience of just using M1 or another synthetic that I can get anywhere. I do buy my M1 at Wally-world since the price is hard to beat for the 5qt jug but sometimes costco sells a case for a real good price.
'12 Focus Red Candy SE Sport 5 spd
'99 Toyota 4Runner Sport
'11 Subaru WRX STI Hatch