GAS: Regular? Premium? Ethanol?

[s219]

this is one of the reasons you want premium,it sours less quickly,has less ethenol,

That's a common myth, but completely untrue. All grades of an ethanol-blend (commonly E10) will have the same percentage of ethanol.

 

[Waldershrek]

****, can't even get ethanol free around here. It's all 10%. I'm more worried about the ethanol than the octane. Dealer said they have a TON of ethanol related issues. I almost went with the Stihl MotoMix just so I could get the ethanol free gas.

 

[Tollster]

That's a common myth, but completely untrue. All grades of an ethanol-blend (commonly E10) will have the same percentage of ethanol.

I guess what I meant to say is ethanol free fuel. You are correct in saying E10 grades are always a mix of 90% gas and 10% ethanol.
Do you think they do the percentage of the mix by the gallon, or by the octane percentage?

I will still stick to my comment on the souring of the premix when placed next to a non ethonol fuel, reguardless of grade I may add, and that ethanol is not designed for two stroke engines, something the EPA has been wanting to cripple for years.

Waldershrek, I have one word, aviation fuel. You will have to readjust your high and low mix according to the owners manual that came with your machine,as well as your idle. Check the plug after the first one or two tanks to be sure you have the high/low/mixture correct. The high/low mix more or less adjusts the fuel/air mixture. You can richen up the high octane with less air.
I set my husky's up according to the owners manual, and run 50:1. You can also go 32:1 if you feel uneasy about the higher octane until you get more comfortable with it. I pay 5.20 a gallon here for av gas at the podunk airport.

 

[joshuabardwell]

People will continue to tell you that and with some continual research you will find that 2 stroke engines where developed to run on high test gasoline.

I will look into it. I have never seen a 2-stroke device's manual call for anything over 87 octane, but I'm not exactly running high-performance equipment. A little Poulan chainsaw, a Cub Cadet weed eater, and so forth.

I actually have to look hard in my area,but with a web search of non e10 premium gas on google I got quite a few hits.

Sure, sure. You can buy non-E10. You see "ethanol free" advertised here and there. But what I'm asking is, if I pull into a given gas station that is selling E10, are you saying the 93 octane is going to have less ethanol than the lower octanes? Everything I've found says E10 is E10, regardless of octane.

Now in this day and age and the rising issues thay have with ethanol deterating carb seals, breakdown of premix,combined with the water absorption

I'm totally with you on the ethanol issue. Like I said earlier, I destroyed two carbs with it before I figured out what the cause was. I'm just not convinced that higher octane gas has less ethanol, generally.

 

[joshuabardwell]

I guess what I meant to say is ethanol free fuel. You are correct in saying E10 grades are always a mix of 90% gas and 10% ethanol.
Do you think they do the percentage of the mix by the gallon, or by the octane percentage?

It's by volume, is what I read.

 

[s219]

The raw gasoline and the raw ethanol are mixed by volume to make the blend (90% gas, 10% ethanol). Then octane is added (it's amount by volume is puny). Most stations have two tanks, one 87 and one 91 or 93. They are mixed to get mid grade 89.

 

[Tollster]

Rule of thumb is anytime you mix oil with you fuel in the recommended ratio, you loose 2 octane points. Therefore, mixing an 87 octane willgive you an 85. Typically and I must say,I have never read any owners manual that recommends anything below an 89 octane on a two stroke.

It will continue to be a long argument,much as an oil thread, I am just happy I am not the one asking the questions and have found what works well for me until they try to cripple us more. I have never had to rebuild a carb unless it sat for years after a purchase,and who knows what they put in the tank,smelled like vinegarand could have been for all I know. I don;t claim to have all the answers,but know enough to keep my stuff running at its peak and outa the shop.

Oh..as for lesser ethanol,no its mixed the same throughout the grades 90/10, but with high octane it is less likely to sour as quick,and your two stroke will run like its intended too.

Its hard ot get good allthe information on a forum,check online for dependable reference sources such as wikipedia and a fewmore and learn allyou can and see what works best for you. I am content and honestly,I am still running 2 year old premix.... No complaints here.

 

[s219]

Rule of thumb is anytime you mix oil with you fuel in the recommended ratio, you loose 2 octane points. Therefore, mixing an 87 octane willgive you an 85. Typically and I must say,I have never read any owners manual that recommends anything below an 89 octane on a two stroke.

I'd be curious to know where you got that rule of thumb (sounds like malarky to me). It would suggest that adding oil into the fuel changes the energy content and combustion properties of the fuel itself, but that's not the case for a two stroke. You know how two strokes work and how the oil separates out into lubrication while the energy in the gas goes into combustion. The octane controls the speed of the combustion (slowing it from and explosion into a fast burn). The octane and the oil are independent.

Technically, the lean/rich tune of a carb is altered by the presence of oil in the fuel and will be different whether you mix 50:1 or 32:1. It's a small difference, but technically true. In that case, it's because the air:fuel ratio is changed for a given amount of mix passing through the carb. But the octane content of the gas itself is not changed at all. It's per volume of gas, and independent of air or oil.

My two newest saws, a Stihl and an Echo, both call for mid-grade fuel or better in the owner's manual (no octane numbers are mentioned anywhere, just "mid grade"). My three older saws, dating 10, 17, and 40 years old, make no mention of fuel grade at all (the 40 year old saw was made in the era of leaded gas in fact).

Some guys on arboristsite did deterioration tests of ethanol fuel, and saw no difference with the premium grades -- it went to crap just like the lower grades. Higher grade fuels do have better additives, but they are independent of ethanol (that has been the case even before we had ethanol blends -- higher grades always had better detergents and additives).

Bottom line is that ethanol blends have a short shelf life, and can really trash a carb if left to sit. In general, the consensus is to not use ethanol blends in a saw if they have been sitting around for more than 6 weeks or so.

 

[joshuabardwell]

Higher grade fuels do have better additives, but they are independent of ethanol (that has been the case even before we had ethanol blends -- higher grades always had better detergents and additives).

Citgo, at least, advertises the same additives in all its grades of gas. If you look around, you may find other brands that do the same.

Bottom line is that ethanol blends have a short shelf life, and can really trash a carb if left to sit. In general, the consensus is to not use ethanol blends in a saw if they have been sitting around for more than 6 weeks or so.

Do fuel stabilizers like Sta-bil change this equation? I had real problems with stale fuel in my saw until I started using Sta-bil. I don't leave fuel in the saw if I can help it, because of damage to the carburetor, but I store fuel for longer than 6 weeks without apparent problem. Somewhere between 8-12 weeks, I toss whatever is left into my car's gas tank and use it up that way.

 

[scrappy isb67]

I guess what I meant to say is ethanol free fuel. You are correct in saying E10 grades are always a mix of 90% gas and 10% ethanol.
Do you think they do the percentage of the mix by the gallon, or by the octane percentage?

I will still stick to my comment on the souring of the premix when placed next to a non ethonol fuel, reguardless of grade I may add, and that ethanol is not designed for two stroke engines, something the EPA has been wanting to cripple for years.


Waldershrek, I have one word, aviation fuel. You will have to readjust your high and low mix according to the owners manual that came with your machine,as well as your idle. Check the plug after the first one or two tanks to be sure you have the high/low/mixture correct. The high/low mix more or less adjusts the fuel/air mixture. You can richen up the high octane with less air.
I set my husky's up according to the owners manual, and run 50:1. You can also go 32:1 if you feel uneasy about the higher octane until you get more comfortable with it. I pay 5.20 a gallon here for av gas at the podunk airport.

The raw gasoline and the raw ethanol are mixed by volume to make the blend (90% gas, 10% ethanol). Then octane is added (it's amount by volume is puny). Most stations have two tanks, one 87 and one 91 or 93. They are mixed to get mid grade 89.

when I first started driving, the gas stations had 3 choices, 87, 89with ethanol and 91
what i was told the 89 is 87 plus ethanol. because the ethanol is higher octane than gasoline.


the only avantages a 2 stroke has are lighter weight, more compact and cheaper to make. but the disadvantage is they have a very narrow powerband and are dirtier than a comparable 4 stroke.
finding a compact 4 stroke is difficult to find and is more expensive than a comparable 2 stroke, but they are becoming more readily available.