Just spoke to the service department manager at the local Toyota dealership to set up an oil change to be done the same time they inspect my tires for the recall. I asked him if switching to a synthetic would be beneficial and he said "not really". I also asked him about Amsoil and he had no idea what it was. Could someone explain what exactly Amsoil is and how it works, also whether or not it would be beneficial? I got the impression from him that i was some kind of inconvenience to him.