When using Fluids in Vehicles that are Air Cooled IT takes a somewhat different Approach. Red line in the Transmission and Amsoil in the Engine. If your hearing the Gearing in a Buell some of it can slightly be calmed down with 75/90 Synthetic in the Primary case helps. And A Synthetic Oil Stabilizer at each oil Change.No more than 1/4 Quart cup per change to your XB. If you change your fluids on a Regular Mileage basis most Synthetic will work well. Just make sure to use Synthetic.
I've rebuilt many Transmissions on Big V Twins and the Buells Due to wrong Fluids being used OR not changed at the mileage Due to Some think they have a Buffer to go a LOT Further on the Synthetic. NOT So! The Transmission Especially the Buells need the Thicker Fluids due to the Heat Issues.
Redline works well in the Trannys,as well as Amsoil.
Royal purple doesn't work well in Motorcycles. In over Thirty Years its' never been on the Display or on the Shelves here in the shop.If you put lots of Miles on your Bike Every Month, Maintenance goes a long way. Good luck !*Jimi
