stopped by BMA Cycles in Bainbridge, PA (local Genuine dealer) to get my Honda Shadow inspected and asked their tech what they're using in the Stella 4T's coming back in for service...
dependent on what the customer wants...
synthetic...Amsoil 10w-40 Scooter Oil
conventional...Castrol GTX 10w-40 passenger car motor oil (they've been using Castrol GTX pcmo in scooters & motorcycles for years without incident); they also sell Maxima conventional motorcycle oil which would be my choice (from their selection) for conventional oil in a scooter which has higher amounts of additives for wear protection, cleaning, corrosion protection, and negating acid effects
I'm gonna widen this conversation a bit...for wet clutch applications avoid any oil that has the API starburst symbol and phrases 'energy conserving' or 'resource conserving' which have antifriction ingredients that might contribute to clutch slippage; following this advice opens riders up to a wider selection of oils to choose from (40 & 50 wt car oils, 30, 40 & 50 wt heavy duty engine oils, scooter oils, motorcycle oils)
I'll confess that even though I have a stash of Spectrto conventional motorcycle oil (clearance sale at Cycle Gear), I am currently using SuperTech 15w-40 in my Suzuki GZ250 and a witch's brew (various leftover 10w-40 motorcycle oils, 15w-40 oils, and a bit of 10w-40 car oils) in my Honda Shadow for short run OCI's for 'flushing' purposes; both bikes are running and shifting well...
if it were me, use the Defy for your next OCI (consider it the tail end of your break-in period) and switch to the Mobil 1 after that...I was just trying to let you know there are lots of choices (some very expensive) and many riders successfully use conventional or synthetic blend oils; one example is Shell Rotella T 15w-40 conventional which carries JASO-MA rating for motorcycle wet clutch applications (usually less than $4.00 per quart) that rivals many more expensive motorcycle/scooter oils
good luck and many miles of trouble-free riding!!!