I started out with Mobil 1 R 20W50 from the dealer I got my 06 America from. The dealer talked me into trying the Amsoil because it was a little cheaper, still in the 50 weight. My mileage dropped way off. Probly not the oil because I went back to the Mobil 1 and the mileage never picked back up. Since then I've used Mobil 1 fully synthetic automotive oil with no adverse effects with my clutch or engine but preferred the Mobil 1 R synthetic but could only get it in 10W40 at my local parts stores. Thats what I mostly used in the bike but the last oil change I wanted to go back to a 50 weight oil to dampen down the top end noise that is typical with our engines so I used Valvoline fully synthetic 20W50 Motorcycle oil. It quitened down my engine's top end. Immediatley after changing my oil to the Valvoline I put 1132 miles on my bike on a ride to Dallas Texas and back. It purred like a kitten there and back. It's got over 42K miles on it now and running great. I usually put around 7000 miles on my bike between changes. My clutch is still strong and not slipping (I weigh in at 300lbs). I have my valves adjusted regularly per maintenance recommendations. I feel confident to load up and head out in any direction at any time on my bike with minimal prep. Any oil that meets the standards outlined in the owners manual should serve you well. The only 50 weight Mobil 1 oils my local auto parts store will carry is for V-Twins. If the Rotela is cheaper I may try it next time I change.
