Don't dare leave E10 in there over the winter.In previous years i always ran what we in europe call E0 fuel which is octane 98 gasoline with 0% ethanol, this because i know that this is easier on the fuel lines/gaskets and does not attract moist or leave behind residue as much as E10 which is the regular octane 95 with the legal requirement of 10% ethanol for emissions(scam).
However with the recent rise in fuel prices and even normal E10 fuel rising above 2 euros a litre i decided to now switch to the cheaper E10, this because it was more like peace of mind to run the simple carburated 2008 Honda hp 20 4 stroke outboard 380cc 2 cylinder on the fuel more or less designed for modern turbo cars with the higher octane rating, in theory this motor as a normaly aspirated motor should benefit from a lower octane fuel.
My only concerns are:
- Because ethanol is hydroscopic the fuel absorbs moisture from the air, all modern cars have vacuum sealed fuel system/tank so that is not a problem. However my boat just has a oem plastic 25l tank with a vent screw on the cap. The tank is in outside air/rain etc.. and is not covered. i can not close the valve because i tried this before but if the sun kicks in it almost explodes because of the pressure build up
- My honda owners manual says that the system is designed to run max 10% ethanol fuel, i use the boat a lot and eventhough it doesnt consume a lot its more or less empty every month so i dont see the deteriorating of the ethanol as hazard like it is with a lot of classic vehicles.
-Outboard motors run at lower water/oil temps and eventhough my engine sees a lot of hours at full throttle 25 knts the nr1 problem with (carburated) outboards is fuel diluition at (cold)trawling speeds which is invitable. Last year my oil also came out pitch black like it came out of a 15k oci diesel engine oil change and smelt like gasoline.
Will the ethanol/fuel in the oil be a reason for problems because the motor spends its life in such a humid enviroment? I mean problems that can be created by the ethanol.
Let me know if you have any experience on this topic and if theres something i am missing out on.
-Powerwise do you think there will be any (marginal) difference? This is not a 2.5 bar boost world rally car but a carburated 380cc 2 cyl 4 stroke with 20hp. Generaly speaking the lower the octane the more power it would have. It has no knock sensors so everything is fixed.