unbidden

I apologize in advance if this topic has been discussed add nauseum; I tried a search of the forums and came up empty. With extra additives being pumped into our gas, in particular ethanol, are any of you experiencing problems. I have been told by a few Yamaha owners that if the bike sits for a week or two there may be problems starting. It has been suggested to add a little Marvel Mystery Oil to the gas as well as octane booster. From what I've read, there is no need and no benefit to use fuel above an octane level of 87 (US) (PON) if your bike is factory designed for 87 octane, thus why use octane booster. I'm riding a V Star 1300 just purchased two days ago. Do any of you use additives and how much to use per gallon or tank full? Any input appreciated.