I've been using the Amsoil 5W-30 ASL since Monday. As expected, the engine runs smoother. But it's always like that after changing to fresh new oil. The real difference I notice is the engine seems more quiet and less vibration. As for performance, I haven't had the opportunity for spirited driving.
I changed the tranny fluid at the same time. I didn't have any 3rd gear problems, but I decided to change anyways in case the 3rd gear problem happens with age or wear. Shifting is butter soft smooth. Seems effortless for the car and driver. Definately worth the 20 bucks.