Do you have a 'special' manual? Well...for my 929 (Service or Owners) manual there is no mention of NOT using synthetic. There is however a statement about using incorrect 'type' oils. SG/JASO MA is the type certification the oil should have for a moto use (resolves clutch slip problems).
I have been using Amsoil 10W40 Synthetic since 5k miles (now have 28k miles) with no problems, only positive results to speak of (shifts better, longer duration between oil changes, etc).
ALL of my vehicles are being converted to Amsoil (one more to go). Buy it by the case with a Preferred Member discount - you wont be disappointed.
