Ducman,
First off, Welcome to the boards!!!!
When it comes to Oil you will find that opinions vary but follow a common theme.
Mobil-1, Agip, Motul.
Coming from a H-D background I COMPLETELY understand the concern.
There is no equivalent to "Harley oil" for Duc's.
Harley was smart, put their label on the lowest bidder that met their specs and then specified the stuff.
Someday the gang in Bologna will get smart and do the same.
I run Mobil-1 15-50 and have yet to have any sort of issue.
Unlike the H-D the engine lube also does duty in the gear box on a Duc so Dino oil wont last as long.
In that vein, the synthetics make more sense.
I just don't understand why Shell Oil dosn't sell their full line here in the states where we, more so than any other people on this planet, consider our cars and bikes family and represent the largest market.
Oh well... Mobil-1 at Wally world runs about 5 bucks a qt.
Order some compression washers, buy a case and run all year without worry.
All the best!
S-28