# Is premium gas better for a 2 stroke or no difference?



## Jayhat (Aug 3, 2012)

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## Jayhat (Aug 3, 2012)

This probably goes in general discussions but I never go there. Sorry

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## avantifishski (Apr 8, 2012)

My guy says use 89 octane

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## Jayhat (Aug 3, 2012)

It's always good to have a guy to tell you stuff.


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## Misdirection (Jul 16, 2012)

I use 93 octane with marine fuel stabilizer w/ethanol treatment in every tank for everything from boat motors to chainsaws. I switched when one of my employees who is a volunteer fireman couldn't get the jaws of life started at the scene of an accident and that was the recommendation after the follow up inspection. I will say I believe it makes a big difference.

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## Jayhat (Aug 3, 2012)

I have a 15hp Gamefisher if it makes a difference.


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## Misdirection (Jul 16, 2012)

Jayhat said:


> This probably goes in general discussions but I never go there. Sorry
> 
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And it really should go in Boats & Motors

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## CowboyWyatt (Mar 2, 2013)

I had an experience that cost me big money in carb cleanouts at the end of my lawncare season. I used 87 octane because someone talked me into it due to cost. 87 leaves a white deposit behind and compromises performance and eventually has to be removed. 
I use strictly Marathon since it is a domestic very clean 93+ octane, echo 2 stroke oil mix, and seafoam stabilizer and injector treatment. For boat motors, I would use a premium oil for the mix. 
After I went back to 93 octane, no more problems with mower or hand-held equipment of any kind. 26 years in business and still have my original hand equipment. Only very minimal basic maintenance has been needed. That should also translate to boat motors as well. 

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## T-180 (Oct 18, 2005)

Also, besides using between 89-93 octane, try using a synthetic oil, you won't believe the difference.


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## Jayhat (Aug 3, 2012)

I didn't know they had synthetic 2 cycle oil. Do you know brand names?


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## Net (Apr 10, 2004)

I started using 89 for all my 2-cycle engines after purchasing a portable generator last year rated for 89 octane. I would hate having to store separate octanes in different containers.


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## ErieRider (Mar 23, 2010)

Jayhat said:


> I didn't know they had synthetic 2 cycle oil. Do you know brand names?


I run the 100:1 amsoil synthetic two stroke in everything from my ice auger, small outboard to weed wacker. I run it 80:1 however and they run awesome with little smell, sputtering or smoke with easy start up. I am probably going to open the whole ratio synthetic debate but can tell you my stuff runs much better on it. The cost of it equals out to how much less oil I use compared to conventional.


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## Legend killer (Apr 20, 2011)

With the fuel treatments of today its overkill to run 89 or 93 in your marine engines, IMO.


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## CowboyWyatt (Mar 2, 2013)

89 octane is still a gamble. Remember, 87 is a junk fuel and contains deposits. 89 octane is achieved at the pump by means of valving between 87 and 93, thus, junk at the pump. 93 strictly. Also, Marathon owns Speedway, one in the same. Synthetic oils should be good. I was just passing along my experiences with high quality equipment properly cared for. 26 years of high rpm daily use is pretty remarkeable. 

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## Jayhat (Aug 3, 2012)

You guys have a wealth of info and share it freely. Truly cool!


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## Tightlines (Jun 29, 2012)

I aso highly recommend Amsoil 2stroke oil and Startron fuel stabilizer.


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## CowboyWyatt (Mar 2, 2013)

Keep in mind; when you go to 93 octane and synthetic oils, you may need to lean the mixture some for top optimum performance. That is achieved by an old school mechanic who sets the rpm to factory standard and then looks away, with tools in hand, and sets it again by ear. High octane also means the motor is going to run hotter. It may be mitigated by synthetic oils. Synthetics work best in new motors. In older motors, seepage may develop due to the synthetics cleaning up years of crud buildup on gaskets and seals. 
Save your money by doing things smart with the 93 octane. Anything else will cost you money. The 4 pieces of equipment I had cleaned, cost me $800 out of a year's budget because I listened to someone who didn't have a clue. Jaws of life is a case in point. When someone's life counted, they didn't work, because of cheap gas. 
The very best counts, starting with equipment. Do your homework. The rest of us are here to help. 

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## I Fish (Sep 24, 2008)

CowboyWyatt said:


> 89 octane is achieved at the pump by means of valving between 87 and 93, thus, junk at the pump.


That's not always the case. There is a true 89 octane fuel. The way to find out if a station has it is by looking at the tank lids. White is 87, blue is 89, red is 93, yellow is diesel, and brown is kerosene. If there is no blue lid, then yes, it is being blended at the pump. 

I thought the only real difference between octanes, other than price, was the detonation points. 87 detonates earlier, and the higher octanes later. I don't believe there is any difference in quality. Higher octanes are required for higher end sports cars/imports. Running the wrong octane will mean you're essentially running the wrong timing. Your spark will be a little to early or a little to late. I've been running 87 in my outboards for years with no trouble. 

The only additive I use is Gas Shok, of which I can't say enough, other than everybody I know that's tried it, swears by it.
http://usafuelservice.com/products.htm


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## ostbucks98 (Apr 14, 2004)

I dont mean to offend anyone but this could be the most mis-informed thread ive ever seen.

Octane rating only deals with compression required to detonation....your mowers being gummed up were most likely the result of ethanol blended into todays fuels or just some dirty gas. By running 93 octane your just burning hotter and burning more money. Unless your application specificaly calls for 93 octane your wasting money. 93 octane is for higher than normal compression engines and may cause or reduce ping or knock. No golden rule here. 
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## CowboyWyatt (Mar 2, 2013)

Let me say again, some stations mix at the pump. In other cases, 89 octane is mixed as it goes in at the tanker filling point. Either way, ?9 is a mix of 87 and 93. Look it up on the web, don't believe me for a minute. I can tell you 87 octane cost me enormously. 93 has never given me any trouble. Only when I went to a cheaper gasoline did I have trouble. The record speaks for itself. I know others who had the same issues. 
Don't cheat the oil mixture in two strokes. Too little will cost you a motor. 

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## GPtimes2 (May 14, 2006)

If fuel becomes harder to detonate over time, it is definitely not due to a "loss of octane." The higher the octane rating, the more resistant it is to detonation. Higher octane fuels are required for high compression engines. In a high compression engine, a lower octane fuel would preignite (detonate from compression, rather than from the spark), causing "dieseling" or "knocking." There seems to be a common misconception that higher octane fuels detonate more easily or more "powerfully", or otherwise have more energy in them. That's not necessarily the case. The octane rating does have to do with the proportions of iso-octane and heptane in fuels, but the rating is really just a measure of the antiknock properties of the fuel. So I would say, run what your motor calls for in the manual unless your having problems. If higher octane solves your problems, then fine, but don't waste your money for a "just in case it helps".


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## misterbreeze (Dec 19, 2011)

Unless your using 100% gasoline, they all have ethanol in them. Ethanol creates moisture in the tank if it sits there a little while. In cars its okay because you go though it faster,but in boats, lawn mowers, etc. it sits longer. Gas that is 87% octane has more additives than higher octanes. I just use 87% octane with Seafoam addditve that has moisture guard in it.


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## M.Magis (Apr 5, 2004)

ostbucks98 said:


> I dont mean to offend anyone but this could be the most mis-informed thread ive ever seen.


Isn't that the truth! 
Wow.


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## backlashed (Mar 19, 2011)

Jayhat said:


> You guys have a wealth of info and share it freely. Truly cool!


Yea, like junk bonds.

Octane has *nothing *to do with quality.

Gptimes has it right. For another poster to call 87 octane "junk" is flat out wrong.


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## Bostonwhaler10 (Apr 30, 2012)

When I bought my last boat the dealer mechanic said to use 87 because the more expensive fuel are older and grummier because they sit around longer.


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## crappiedude (Mar 12, 2006)

ostbucks98 said:


> I dont mean to offend anyone but this could be the most mis-informed thread ive ever seen.
> 
> *Unless your application specificaly calls for 93 octane your wasting money*.
> 
> posted using Outdoor Hub Campfire


I couldn't agree more.
I use 87 octane in my 1994 Outboard, mowers trimmers and everything else that calls for it and never have any trouble. I will say I use Stabil in everything but my autos.


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## slimdaddy45 (Aug 27, 2007)

Look around for 90 octane recretional gas it has no ethanol in it I haul gas and we have only 2 stores we deliver it to and there down along the ohio river Marathon is the only rack we can get this gas so Im sure some marathon stores have it and if your around Logan we sell it at our bulk plant plus if you wanna mix your own 89 it is mixed at 66% 87 and 34% 93 makes the 89 octane the one store we do in Gallopolis sells alot of the rec 90 to boaters down there


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## backlashed (Mar 19, 2011)

Some sources on this discussion.

FTC Consumer Information keeps telling the reader to refer to the owners manual. Good Advice.

Here is a link to Exxon/Mobil.

You can check out this article at howstuffworks.com

Here is something from the Minnesota Dept of Commerce. See page 2.


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## Eriesteamer (Mar 9, 2007)

In all my years I have yet see any 2 cyclers use any but regular and I have had lot to do with them. We had what was called white gas back them days that was best to use in 2 cycle outboards. Now there putting out 4 cycle ones I got no info to give you but to read your user guide that came with motor. Or call on a dealer who will tell you.


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## Misdirection (Jul 16, 2012)

Going back to my original post, I said to treat your gas with Marine Stabilizer with ethanol treatment. See link below regarding Mercury Marine's recommendation. Keep tanks full, treat with marine stabilizer. Ethanol makes up 10% of the gas (aka E-10) and once it starts to break down you loose up to 3 octane numbers. So my take is the higher octane gas is making up for this. My post had nothing to do with a debate between 87 vs. 93.

http://www.marinepartsexpress.com/ethanol.htm


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## eatinbass (Aug 6, 2012)

Eriesteamer said:


> In all my years I have yet see any 2 cyclers use any but regular and I have had lot to do with them. We had what was called white gas back them days that was best to use in 2 cycle outboards. Now there putting out 4 cycle ones I got no info to give you but to read your user guide that came with motor. Or call on a dealer who will tell you.


My old Mercs have Marine White Gas listed in the manuals. I'll second READ your manual


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## Uncle Paul (Jul 10, 2004)

GPtimes2 good explanation but if I can add a few things. A result of the higher octane is that 93 octane burns at a slower rate than 87 to control the detonation and in some 2 cycle engines the exhaust ports open up before the fuel is fully burned so yes you are wasting money by burning the 93 octane fuel if your engine calls for 87. Now speaking in general terms (because there is always an exception) 93 and 87 create the same amount of power in your engine, the additives that are added to create the different octane ratings are for burn rates of the fuel. However a few guys that have carbon deposits on a piston crown or on a cylinder head that will cause hot spots that could ignite the fuel will run 93 and have a better running engine, but they would be better off running some carbon removal additive and fixing the problem. The engine manufactures spend lots and lots of money to develop the engines why do people think they would not know what fuel to run in them.


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## KaGee (Sep 8, 2006)

The Blade had a big article on this topic in Sunday's paper.

Several "experts" quoted. You are wasting your money unless you have a high-end, high performance engine, or the engine manufacturer explicitly calls for higher octane.

Personally, I don't consider a 15hp outboard to be a "high performance" engine.


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## PapawSmith (Feb 13, 2007)

KaGee said:


> Personally, I don't consider a 15hp outboard to be a "high performance" engine.


Oh yeah? Well take it off the back of your boat, perform a few functional and cooling modifications to it, and stuff it on the back of a go-cart and tell me what you think about it then.


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## avantifishski (Apr 8, 2012)

Thought it was about ethanol content not octane, when we talk outboards

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## Bazzin05 (Feb 2, 2011)

I Fish said:


> The only additive I use is Gas Shok, of which I can't say enough, other than everybody I know that's tried it, swears by it.
> http://usafuelservice.com/products.htm


I've been using marine sta-bil and sea foam for the last few years but I just purchased some of the Gas Shok to give it a try. Looks like a good product.


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