Sorry to chime in late, I have been away from the board for a while. If I was the OP, I would go with Motorcraft oil, either the blend or full syn. M/C filters and follow the recommended OCI while under warranty. Motorcraft oil (Conoco-Phillips), meets all of Ford's specs and there would be no-doubt if a warranty claim should arise. The dealer is probably selling Amsoil Xl at the usual stealership markup (75% or more) and will tell you to come back in 3K miles (maybe 5K). It is just more incentive to get people to come into the service bay. They may shoot themselves in the foot though, if they install non API/Ford Spec oil, especially when a warranty claim should come through the door.