I use Valvoline 10w40 in my mustang with WIX filters. If i felt the need for synthetic in it, i would run Mobil1 or Amsoil. My Saturn gets mobil 1 extended milage just because I dont want to change the oil as often. My crotch rockets, they are very finicky with oil, as they use wet clutches. The ninja loves mobil 1 4T, and the Suzuki Amsoil. Swap the oils in them, and you definitely will notice the feel in the clutch and hear the difference in the valvetrain.