What type of gas to use?

[wallyuwl]

I can get no ethanol 88 octane gas from Fleet Farm. Is it suitable for a 1985 Johnson 90 HP V4 outboard? Or should I stick with 91 octane no ethanol? There is about a 30 cent per gallon difference, which is pretty big considering the main lake I go on is large and I use about 3 gallons each time I go out (which can be 2-3 times per week). I will be running Seafoam in the gas tank as well as I do with all my small engines.

 

[t2stroke]

The motor doesn't really care. 87 octane is fine with or without ethanol. Ethanol is blamed for a lot of things. It is mainly hard on rubber & some plastic parts of the motor. If it is left to sit then it suffers from what is called phase separation. Ethanol (the alcohol) has an affinity for water (moisture in the air). When this gets added to your fuel then let sit it separates. That is not good & causes running issues.
If you check/Google (pure-gas.org) you can find out if there is a source for ethanol free fuel in your area both US & Canada.
On another note you can save more money by not putting Sea Foam in your fuel on every fill up. No particular benefits in running constantly. JMHO

 

[kevinj]

88 octane is just fine. I run Stabil 360 in all my boat engines for a little protection against moisture and phase separation. Seat foam in every tank isn’t necessary.

 

[timguy]

Another problem with ethanol is that it actually provides an octane substitute and once separated, the fuel can case pre detonation, resulting in potentially serious engine damage. With respect to performance, ethanol fuel is less efficient at producing combustion, therefore slightly less power and economy in most applications.....go ahead, don't take MY word for all this.....Google it up, then do some performance checks as well as economy checks.
Octane isn't real critical on 2 strokes, you can use the 88 just as effectively. 4 strokes with over 9.5 to 1 compression ratio should really run octane above 90. That's just my opinion, take it with a grain of salt. Only been building motors and engines......self employed, for 52 years....what do I know?