Thing is, you can rarely talk to the actual designers
of an engine - usually you're limited to what the retailer has to say... and they'll say jus' about anything to A: sell you something & B: cover their behind when it comes to potential warranty claims.
So... I tend to nod & smile w/sales reps - but I listen to folks that have the actual experience to back it up, people with nothing to gain save the exchange of information.
I should prolly mention that the only
reasons I run 100:1 is less buildup in the engine and having to buy far less oil... it's really not that important an issue, conventional or synthetic - whatever works for you