Oil questions are hazardous but the simple answer to the unavailability oil Ams- -- is do like Victory does and mix standard oil and synthetic oil and make your own synthetic blend. You can also use any straight synthetic but what ever you do make sure the oil you choose is compatible with motorcycles. Victorys use a wet clutch and are single sump (transmission, primary, engine all use the same oil) so using oil that isn't compatible will affect you bike. I.e. your clutch will slip.
Retired USAF, IYAAYAS!
2008 V-Star 1100 Custom Bobber project
2011 Crimson XR with Forged Highway Bars / Hard Bags / Passenger Backrest, Ness parts including Smooth Layback Plate Frame/Mount / Rad 3 Mirror / deep cut grips / drivers floorboards /shifter peg / brake peg / passenger pegs. Witchdoctor black rack, Lloydz filter / timing wheel / VFC III, 7Jurock windshield, Drag Specialties seat.