Hi, I just recently switched from Mobil 1 to Amsoil. I received there Action news magazine where they claim they have Mobil 1 beat. One thing that bothers me that has been posted before, is the accuracy and quality of there data. I can't seem to find any other independent labs that can compare the two. Amsoil is no doubt good oil, and maybe slightly better due to the additive package they use, but is it worth it? I'm thinking of going back to a 0w-30 Mobil 1 for the winter and being I can buy it off the shelf is great. I notice Amsoil doesnt put the shearing test on there websited bc Mobil 1 matched it, even before super sync came around. I always thought this was a really important test? I also like the fact that Mobil is factory filled in the best cars in the world. This could be due to Mobil's corporate strength and production capabilities or simply becasue it is the best oil......