Which gas is best

[piggy]

Read different opinions on proper gas to use in 2-stroke outboards. If mixed at 1/50 with a good oil should you use 87,89 or 91 octane? What about that gas that the octane rating is raised by adding ethaniol at the 10% level good or bad? Will a higher octane smoke less and burn cleaner? What about age of motor if oil mixed is correct? Thanks!

 

[5150abf]

Re: Which gas is best

Higher octane gas actually is actually harder to burn, it is made to fight preignition (knock) in high compression engines.

A 2 stroke outboard is a relatively low compression engine so the lowest octain is fine.

What I have heard about ethanol is it may eat some seals in older carbs but you shouldn't be able to tell a difference, don't have to deal with it here yet.

As far as smoke, it is the oil in the gas that smokes so what gas you use won't smoke more or less that you can tell, I have read synthetic oil smokes less but the gas shouldn't make any difference.

 

[tashasdaddy]

Re: Which gas is best

the motor were actually built to run on 87 lead free gas, the ethanal was a slight problem, as the alcohol in the gas cleaned the systems, and the gunk go into the carbs. the synthetic oil burns cleaner and less smoke. but 87 octane, and any TC-W3 rate oil is fine to run.

 

[kenmyfam]

Re: Which gas is best

I have always used 87 octane unless it is not available then I have had to use a higher octane. never really noticed any difference except for the cost.

 

[triumph190]

Re: Which gas is best

Something else to keep in mind when choosing gas is, "fresher is always better." You want to put the freshest gas in your tank. I would say 99.9% of people that buy gas for automotive purposes use 87. This means gas stations have to fill their 87 octane tank more often. The more the tank is filled the fresher the gas.

 

[Woodnaut]

Re: Which gas is best

Triumph makes a good point. One other item to consider is where you buy your gas. In the large metropolitan area that I live in, all gasoline - by law - is at least 10% ethanol. Some of it is 15%. Unfortunately, I suspect that some of it contains a much higher percentage of ethanol. I recently read that some retailers have been selling gas that contains as much as 48% ethanol. This is apparently because some of the less reputable fuel dealers will cut gasoline with ethanol as a means of stretching their profits. For this reason, I buy gas only at the majors - and even then only at a station that appears to be a well managed franchise. I realize I could buy it maybe $0.20 per gallon cheaper down the road, but that's a total savings of less than $5 a tank. Don't get me wrong - $5 is a nice chunk of change, but it's not worth putting dodgy gas in a boat I have already spent a small fortune on.

 

[Randybeall]

Re: Which gas is best

Ethanol is added to gasoline as an oxygen source. It will cut fuel milage while producing a cleaner burning mix. If you live or boat far enough from metropolitan areas many stations still have non ethanol fuel. Our engines thrive on it. More power available per pound of fuel.
Low octane is fine in your two stroke engine, like already mentioned, these are low compression engines. Regularly add carbon remover to your fuel or make a point of doing a decarb with some of your favorite addative. Carbon build up is a very subtile power killer.

 

[pecheux]

Re: Which gas is best

As I mentioned on another thread ... my 15 hp Force OB idles smoother with 91 octane gas instead of 87 ... I dont know why ... I do perfect 50:1 mix using synthetic oil.

 

[mthieme]

Re: Which gas is best

All mine run fine off of 87 octane.

 

[mickjetblue]

Re: Which gas is best

Depends on what what standards you are judging by.

I think that 91 octane provides a little better performance than 89 or 87 octane.
I agree that the lower octanes work good, but that might have something
to do with a slight decrease in performance.

I base this on several times when I have purchased the lower octane gas, and
noticed a slight decrease in performance, as well as mileage. This is only my
2 cents, 'cause I ain't got no statistics to back it up.

I buy the mid grade fuel, usually.