I've never touched Amsoil. It was impossible to find back when I first heard about it and I'm not a fan of their distribution model (MLM). I only run Mobil 1 Fully Synthetic in all my vehicles. 324,000 miles on my 2007 Suburban and 185,000 on my 2002 Dodge Ram 1500. I replaced the valve cover gaskets on the 2007 Suburban last year and there was not a single bit of buildup anywhere. Other than having the slight yellow color, it was as clean as the day it rolled off the factory floor.