Use synthetic oil in Viking 700?

I run castrol synthetic motor cycle oil 10W-40.

In all honestly, in all my Yamaha's ive ever owned, i've always used the Yamalube, and its really good stuff, but if you want to go the route, i ssanuse Mobil 1 Full Syn in my Can-am Outlander 800, and in our 2011 Ni Murano, and am plenty happy with it. Its about time for our first oil change after the break in service was done, and i'll probally go with the Yamahalube.

With the added weight of the Viking 6, I just want to keep this engine happy... So castrol synthetic has the correct additives for the 686?

My dealer said same thing, Dino oil...no need for synthetic. I was surprised given the premium price they get for Yamalube synthetic.

I've been running Mystic full synthetic in all my Yammys including my Generator for as long as I can remember. Better cold weather properties at start up, holds its film strength better at high temps as any synthetic will do. Go to Bobtheoilguy.com and give yourself a great education on oils.

Only Yamalube in mine

Only Yamaha lube here for now on too. After my brake in I used Honda oil and my wet clutch was slipping bad. I replaced it with Yamaha lube and it fixed it back up. Say what you want, but that's all I'll ever run from now on.

Ill only run yamalube in mine also. Its what my dealer recommended and its what JBS recommends