Re: What is the best Gasoline for 1976 Outboard Johnson 70 HP?
the E10 itself isn't an issue, especially for a workhorse motor like that, if it's fresh. The problems (often debated) come when the E10 gets some age to it, which can cause it to break down, or over time, attract water, or loosen gunkified stuff in the fuel path since it's an efficient solvent--the loosened gunk causes the problems, not the fuel itself.
Also, because of its higher alchohol composition, it can cause older parts such as hoses and fiberglass tanks to degrade, again sending gunk through the fuel path.
One reason it seems E10 is hard on boat motors is because boat fuel typically isn't all used up in a month, like cars' fuel is. Same with motorcycles. Second, the smaller the motor, the harder to handle the gunk and water. Third, a boat's tank is exposed to more humidity than a car's, so those who agree that humidity is a problem with E10 point to that distinction.
For general recreational use, especially in an old 70, any difference in how E10 performs v. pure gas would be negligable.
I'm doing my level best to describe fairly, rather than advocate, the opinions as to E10.
