best synthetic oil and m/t oil??

[doodoo]

I switched to mobil1 5w30 after my 2nd oil change since I had very good results with it with an older car. Runs good. Almost tried amsoil, but heard that it thickens too much as it gets older. Curious about what kind of synthetic m/t oil I should use. I'm not sure if I trust "off brands" like Amsoil and Red Line. Is mobil1 good m/t oil since they make the best motor oil? Whate are your recommendations? (BTW - I hate large predatory corporations like Exxon Mobil, but there is no denying that the best is the best with Mobil 1 synthetic motor oil)