If you don't mind me asking in your thread...
I can find Ethanol free gas but its all 87 octane. I had wanted to use strictly 93.
Embarrassingly now that I say that out loud I realize I have no reason to back up that desire. I guess I just assumed it would burn cleaner. Any thoughts on that?
I think I went ahead with the ethanol free but cant remember now. Guess I should burn the rest in my car as suggested just incase.....IDK
Solo, higher octane is used to prevent engine knock (preignition.) This is usually needed for higher performance engines. My understanding is that running higher octane fuel in a motor that does not require it will have it burn hotter. I don't know if that's accurate or not.
I have found no problems running 87 octane ethanol free in my motor. And thank god the Subaru specs 87, so I don't have to pay higher fuel costs like my buddy's swanky-danky Acura
There is some debate on another point of fuel system health: run the carb bowl dry at the end of a session, or leave it full? Granddad used to run the carb out every Sunday night before packing up the boat for the week. I have spoken to mechanics, and the one school of thought is to clear out the carb bowl, so the fuel in the carb doesn't heat and oxidize in the sun all week. The other school of thought is that if you run the carb "dry," there is still a little bit in the carb bowl, which will then be more likely to evaporate away leaving some nice varnish in your carb. So don't run it dry.
On the little 2hp Suzuki 2 stroke, I would run the bowl dry every time I ran the motor. As in, running out from the dock to go sailing, shut off the tank and run her dry. Coming in from sailing, shut off the tank and run her dry. The reason for this was if there was any fuel in the carb, and I tilted the motor, it would dribble out the air intake and stink all damn day long.
On the Nissan 4 stroke, I have gone 2 seasons now NOT running the carb dry, except for Fall winterizing, when I drain the bowl fully using the drain port. However, I have had the opportunity to sail up to 3x a week, which is weekends, and then maybe up to 2x on weekday evenings after work. That fuel has been run through the carb plenty. This year, I have only been out in the boat I think 3x so far. Not good. But now the only room in the house yet to be unpacked and fully set up is the office, so I think I can start sparing some time for the boat! Boat can't be too envious of the house, because Boat will now have a nice place to park for the winter!
As for issues with low speed idle, I have heard of, and actually seen, more issues with the Mercury badged motors, but to be fair I have also seen some Tohatsus with issues. Best example is a friend with I think a 6hp Tohatsu similar to my Nissan in age, that she never used ethanol free, treated the fuel, or winterized the motor. That motor sat through two winters on the back of the boat, with no service. She did get away with this having a reliable motor for 2 seasons, UNTIL she went to sell the boat. She had the prospective new owners out for a windless cruise to show them the motor operation, when I konked out on her. I was nearby drifting, drinking beer, and chatting with another becalmed boat with an attractive female type aboard. I did everything I could with that motor, guessing it was fuel system, and couldn't get it started. She was all "I never had problems with this motor" to the buyers, to which I did agree - she had never had problems. I bit my tongue on the lack of maintenance, though. Took it to the local wrench, and he cleaned the carb and put in a new sparky plug, and doncha know it ran again, no problem. I felt vindicated on 2 counts: 1) I correctly diagnosed the issue 2) I'm dang happy I treat my motor the way I do, what with ethanol free treated gas, and fogging it for the winter and keeping it in the basement rather than hanging in the freezing cold.
I think Granddad would be proud, he taught me well!
