My oil injection system on a '02 90 hp put out 80:1 fuel to oil for idle and somewhere on the way up to WOT it increased the oil to 50 gas:1 oil. Manual said that the engine didn't need all that much lube at low speeds. Hands down, BTDT, synthetic or synthetic blend smokes less......less smoke means cleaner combustion chambers.
Other thing I learned on this site when I joined was the use of Sea Foam (snake oil).....most all auto stores carry it. It has light mineral oil, naptha, and alcohol for ingredients and has been around for 50 years. About 7 bucks a can. The can says 1 oz. per gallon and that's what I used on my 90. Bought it in 2004 as a 2 year old used engine, used the engine VRO oiler for 10 years and didn't do any carb work. Later I had a look at them and they were clean and my engine smoked very little using Pennzoil TC-W3 semi-synthetic oil from Wally World.
So, why not take a spare tank with 80 parts gas and 1 part oil if you're worried. If you think you are going to speed up, switch to 50:1.
Other thing is to tilt your engine up some what so that fuel doesn't have the opportunity to puddle in the cylinders. Back in the '60's Mercury developed a whole line of low HP fishing motors that were tilted like that for that reason and to help the lower unit slide over logs and such.
Last, periodically, shift into N and rev her up to a couple thousand rpms. If she burns clean you are good to go. If it smokes, run like that till it clears up and go back about your business till you feel like doing it again. I used to do both those things when I trolled a lot and both tricks work.
Good boating.
Mark
