Gas additive?

[Bushwacker]

That's an upper cylinder lube; might be ok to use if you have sticking valves or as a fogging oil for winter layup, but don't see the need for summer use unless you like changing fouled spark plugs! If you're running E10 gas, I'd be more inclined to add Marine Formula Stabil (AND check the ethanol content of the fuel!) I'd also be inclined to install a good large diameter (2 5/8") vacuum gage to monitor engine load at cruise and detect any changes in performance/engine health in the future. It's also sensitive enough to detect build up of barnacles, etc. on the hull and running gear! Denny