MPG difference between Amsoil 0W30 and 5W30

[ConfederateTyrant]

The kinematic viscosities aren't what the increase in mileage would be from. The Series 2000 0w30 contains more friction modifiers (according to post from TooSlick and TeeDub, maybe Pablo too)to give the best wear protection and to help out with gas mileage increases. The XL oils do contain friction modifiers, but maybe not the same as the Series 2000.