I used to drive an Olds with a 3.1L V6 and I first tried Amsoil 10w-30 and liked it. Small mpg boost and cooler running according to the gauge. Tried Mobil 1 next and prior benefits disappeared. Tried Valvoline Syntech and it was more like the M1. I read that Valvoline buys its synthetic base stock from M1. Now I read that "synthetic" oil is ultra pure dino stock! I now believe that quality brands of conventional oils are all you need for average applications.
