octane

[ralphl]

read a post a while back that seemed to claim lower octane gas was better for outboards I always go for 91 oct without ethenol. Am I wrong???.. Yammy 4 hp 4 st..Nisson 9.8 4 st and Suzuki 55 hp 2 st.. What is the best gas??

 

[ondarvr]

Re: octane

You can read for days if you do a search on this subject.

The best fuel is the one listed in the manual for that motor, typically its 87, any higher octane will do nothing for you, only cost more.

 

[Silvertip]

Re: octane

Just because it is 91 octane does not mean it doesn't have ethanol. Read the pump. In some areas it is not required that the pump be labeled with the ethanol content.

 

[ralphl]

Re: octane

ethanol without saying so?? That is scary. How can we tell if it has corn crap so we dont screw up a motor??

 

[ondarvr]

Re: octane

If you can avoid it, do so, if you can't, don't worry about.

 

[Brewman61]

Re: octane

ethanol without saying so?? That is scary. How can we tell if it has corn crap so we dont screw up a motor??

Here in MN, right smack dab in corn country, 10% ethanol is in almost all gas.
That includes all grades, regular thru premium. I don't think that it's even required anymore to state it on the pumps, since it's a state mandate.
The exception is that a few stations sell ethanol free premium that is only supposed to be used for specialized engines that aren't suited to run ethanol.
It costs about $0.75/gallon more than the alcohol laced premium.
It's what our marina sells, too. My boat doesn't require premium, it can run just fine on the 87 stuff, and both boat and motor are ethanol approved, but I run the non-alcohol. Engine runs just fine on that too.

You should be able to contact someone at your state who can tell you if ethanol is mandatory in your gas, and if the pumps are required to state it.
Or perhaps if you find a gas station attendee who's knows the laws.

 

[kenmyfam]

Re: octane

Whatever octane is recommended by the manufacturer. Generally 87.

 

[ChrisAG]

Re: octane

Gasoline in a boat typically sits, sometimes for weeks, which is not the case for cars. This means two issues are at play when gas sits for more than a couple of weeks:

1) Gas loses octane.
2) Ethanol blended gas can accumulate water.

Both issues are taken care of if you use 91 octane non-ethanol gas.

 

[JB]

Re: octane

Those of us who think we know it all are danged annoying to those who do.

Pity the poor member who can't tell us apart.

 

[ChrisAG]

Re: octane

Those of us who think we know it all are danged annoying to those who do.

Pity the poor member who can't tell us apart.

Can you be a little more specific in that statement please?

 

[5150abf]

Re: octane

Most people misunderstand the octane ratings thinking the higher the octane rating the more perfomance you get from the gas, can't tell you how many times I have been at the gas station and seen junior putting racing gas in moms Oldsmobile thinking it will make it faster.

Octane prevents preignition or knock that is only a problem in high compression engine, which none of your ourboards are so regular unleaded is fine.

The higher octane won't really do anything but drain your wallet faster but it is your wallet.

 

[Brewman61]

Re: octane

Yup. I remember when BP/Amoco or whoever they were at the time, stated in their advertising that their "Gold" (Premium) grade of gas would do all sorts of things for the vehicle, including more power, better mileage, etc...
It was all B.S., and they were ordered to stop making those claims.

The wholesale price difference between regular and premium is only a penny or two per gallon. But they charge $.20+ per gallon more- so people think it must be better. Like you said, if your vehicle doesn't require it, it just drains your wallet faster, and that's really all it does.

 

[ChrisAG]

Re: octane

Yes - but I was refering to what happens to gas over time as it sits.

Still waiting to see if JB was refering to my post.

 

[tx1961whaler]

Re: octane

Yes - but I was refering to what happens to gas over time as it sits.

Exactly what does happen? Please cite some sources, as I am curious and would like to research this further.

 

[JB]

Re: octane

"Still waiting to see if JB was refering to my post."

Not at all. I was referring to the topic in general and the endless arguments about octane and/or ethanol that I have read here over the past nine years.

 

[Silvertip]

Re: octane

Ahhh -- the old ethanol is "crap" discussion. Having used E10 here in Minnesota since 1997 and having worked on countless engines in that time, the only fuel related issues I come across are those where fuel treatments were NOT used when they should be. One of those times is when you store your boat, lawnmowers, weed whackers, ice augers, chain saws, and leaf blowers for the season. Add stabil or seafoam to the fuel, run it long enough to get the mixture into the fuel system, shut it down and put it to bed. I have yet to see an engine that was "destroyed" by ethanol. I have seen a lot of them that were destroyed by the owners however. Contrary to popular belief, E10 does not turn to an unusable crud in six months, nine months, or even a year. As those of us who store vehicles for six months at a time. In coastal areas there is apparently an issue on boats with very large fuel tanks that don't get emptied on a regular basis. Water separating fuel filters are now being installed on most EFI/DFI engines by the dealers or manufacturers to handle moisture issues. Heck, even my pontoon has one. One last ethanol comment. When gas and E85 prices justify its use, I use E85 (85% ethanol and 15% gasoline) in my 2006 Impala. 60,000 miles later it has never had a hicup. E85 use vs E10 is about 40%/60%. It is not the devil fuel it is made out to be.

 

[ralphl]

Re: octane

so ,,all the tales about seals and gasket damage are unfounded??? I dont have experiance in the matter,, which is why I asked..

 

[ondarvr]

Re: octane

I've used E-10 for almost 2 decades and I don't recall a single problem that could be directly blamed on it. I did have a cork gasket in the float bowl of a 1969 Johnson 6hp breakdown after about 10 years of using E-10, that darn gasket only lasted about 25 years, must have been that evil E-10 that did it in.

Most brands of motors started using ethanol resistant parts in the late 80's and everything you buy as replacement parts is E-10 compatible and has been for a long time. If you haven't rebuilt you carb or replaced the fuel lines since the 80's then its long over due and not the fault of E-10 if something happens to fail.

Now there is an issue in states that haven't banned MTBE, the problem is when its mixed with E-10 and there?s some water in the fuel it can create a goo which will plug things up.
MTBE does the same thing as ethanol but is being phased out because it can pollute ground water.

I don't like E-10 and would use straight gas if possible, but straight gas can be very hard or impossible to find in some parts of the country and will continue to be phased out. This means you have a choice, you can learn to live with E-10 (not hard to do) or stop boating or doing anything else that involves using it.

 

[ralphl]

Re: octane

OK, I feel better informed now than when I posted the question,, and i ask this in all sincerity,.. what good does it do??? How are we better off with the stuff??

 

[JB]

Re: octane

Well, the theory is that ethanol enhancement allows them to not use other, deadly, additives to boost octane for modern cars and it also cuts the need for foreign oil in gasoline by 10%.

I have some firm opinions on the topic that I will keep to myself because all they ever do is troll up and annoy those who know it all.