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Ed Cesnalis

Which gas now?

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I've been using Chevron gas (California) for 11 years and now the station is closed and I have to choose between Shell and Texaco.

My inclination is to avoid Shell because anytime I had bad gas issues in the past it was Shell.

Which to choose?

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I use them all. They all have to meet a standard. Thinking one fuel is head and shoulders over another without scientific testing is about as accurate as trying to outguess the stock market.

The engine doesn't care so long as it's sucking down 91 oct or higher.

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Runtoeat   

We have Meijer stores in Michigan.  This is a chain that tries to sell products and produce that is from Michigan.  Meijer tries to support the local economy.  Their gas stations are clean and well maintained.  I buy my 93 oct. with ethanol here when possible and, although it isn't on Andy's "top tier" list, have never had any problems. I like to support my local stores and think these stores try to do what's good for the local people.  If not able to buy locally, I try to buy is BP gas from large and clean stations.  I'm sure all of the other major names are the same quality.  I would just try to buy from large hi volume stations that appear to be well maintained.

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53 minutes ago, Runtoeat said:

We have Meijer stores in Michigan.  This is a chain that tries to sell products and produce that is from Michigan.  Meijer tries to support the local economy.  Their gas stations are clean and well maintained.  I buy my 93 oct. with ethanol here when possible and, although it isn't on Andy's "top tier" list, have never had any problems. I like to support my local stores and think these stores try to do what's good for the local people.  If not able to buy locally, I try to buy is BP gas from large and clean stations.  I'm sure all of the other major names are the same quality.  I would just try to buy from large hi volume stations that appear to be well maintained.

Thanks Dick, there are only 3-4 brands available unless I'm willing to drive hundreds of miles for it.

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Adam   

In California I'm not sure it matters all that much Ed, all gasoline is refined in just a handful of places (at least for summer blend).  The question is really who is dumping in what additives.   I often wonder about gas v 100LL and is it really worth all the hassle to go get my gas trailer filled and then pump it in my tanks (wondering about quality) or just do more frequent oil changes and use 100LL.   I'm currently using 91 mo gas that I buy up at the closest station (think its a Citgo).  Knock on wood, no water and no issues. 

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ct9000   

Interested to hear why you would use fuel with ethanol in it ? . Ethanol absorbs water and therefore promotes corrosion also is more likely to suffer from freezing problems. You also use more of it - more fuel per hour. I acknowledge that Rotax will tolerate 10 % ethanol but I would not use any fuel with ethanol in it at any price. 

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1 hour ago, ct9000 said:

Interested to hear why you would use fuel with ethanol in it ? . Ethanol absorbs water and therefore promotes corrosion also is more likely to suffer from freezing problems. You also use more of it - more fuel per hour. I acknowledge that Rotax will tolerate 10 % ethanol but I would not use any fuel with ethanol in it at any price. 

My gas absorbs water and therefore reduces corrosion, no?  How can the water corrode when its bonded with my fuel?

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10 hours ago, ct9000 said:

Interested to hear why you would use fuel with ethanol in it ? . Ethanol absorbs water and therefore promotes corrosion also is more likely to suffer from freezing problems. You also use more of it - more fuel per hour. I acknowledge that Rotax will tolerate 10 % ethanol but I would not use any fuel with ethanol in it at any price. 

Many of us use ethanol fuel in their CTs.  Roger has told us numerous times on this forum that it's not a problem, and that matches my experience.  In my area, I have three potential fuels to use, and all of them have downsides:

1) 100LL - Worst choice, the lead in the fuel fouls plugs, valves, and the gearbox, and its use requires increased maintenance.

2) No ethanol 90 octane fuel - second worst choice, the octane rating does not meet the 91 octane minimum specified by Rotax, and could lead to detonation ($$$).

3) 93 octane pump gas - third worst choice, ethanol is not ideal and does have lower fuel energy leading to marginally higher consumption.  

I use the 93 octane pump gas (usually BP brand), and have had zero issues.  I tested the fuel and it actually only has about 5% ethanol, half the 10% it's allowed to have.  Lower grades (87 and 89 octane in this area) might have higher ethanol content.  I have put about 450 hours on my airplane since I bought it, the vast majority of it was on ethanol pump gas.  I wish it didn't have the ethanol, and I'd pay extra for 91+ octane ethanol-free, but it's not available and I really don't want to get into mixing fuels just to get the correct octane.

In my opinion and experience, there is no problem with running ethanol 91+ octane fuels up to 10% if you don't have a better local alternative.  In fact, I read somewhere that there is at least one CT in South Africa flying on the local swill that is something like 22% ethanol, with no problems.  A lot of the problem with ethanol come from vaporization in the fuel system causing "bubbles" in the lines that can cause hesitation, stumbling, and engine stoppage if severe enough.  That is purely a function of fuel system design, and if the fuel system components are kept away from strong heat sources, this is not a problem.  The CT fuel system seems very well designed in this regard, mine has never had a single hiccup.

Again, this is all opinion and I know other feel differently.

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FredG   
19 hours ago, Ed Cesnalis said:

My gas absorbs water and therefore reduces corrosion, no?  How can the water corrode when its bonded with my fuel?

 

The gasoline-alcohol mixture doesn't "bond" to the water (nor does the water bond to the fuel).  Rather, the water is simply dissolved in the gasoline mixture.  It is still water.  Not all that different from water vapor in air.  Metal will corrode faster in humid air than in dry air.  

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Runtoeat   

ct9000, most of us in the U.S. are in the same boat as Andy.  For automotive fuel, there are not many stations that offer non-ethanol fuel in the 91+ octane.  Our government has a policy of making alcohol from corn.  The government then tells the fuel distribution companies that they have hundreds of thousands of gallons of alcohol to find a use for.  So far, these companies have been able to get rid of the ethanol the government mandates they use by "only" putting up to a maximum of 10% in our auto fuel.  91+ octane non-ethanol auto fuel can be found but this is not in abundance.  My experience using MoGas (unleaded 93 octane 10% ethanol) has been a non-event for the 9 years I have used this in my CTSW.  This usage goes from ambient 100+ degrees F with 100% humidity to minus 25 degrees F. and 20% humidity.  I have never found a trace of water when I sump my fuel system.  There is a "plus" to using MoGas.  This has a super low lead content.  If there is something all Rotax owners must avoid, it is using leaded fuel.  100LL Av fuel is loaded with lead and this will choke our Rotax engines.

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18 minutes ago, FredG said:

 

The gasoline-alcohol mixture doesn't "bond" to the water (nor does the water bond to the fuel).  Rather, the water is simply dissolved in the gasoline mixture.  It is still water.  Not all that different from water vapor in air.  Metal will corrode faster in humid air than in dry air.  

Thanks Fred,  Re-thinking...  So Avgas (alcohol free) remains visibly separate where my Mogas contains dissolved water. 

I was reacting to this statement "Ethanol absorbs water and therefore promotes corrosion" and don't see that happening in my dry environment. Is that a valid concern? 

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FredG   

I think the statement, "Ethanol absorbs water and therefore promotes corrosion" is true but the amount of water it absorbs is proportional to the amount of water in the air (i.e., the relative humidity) that is in contact with the surface of the fuel (in whatever container or fuel tank it happens to be in).  So, in a very dry climate, I would expect less water to be absorbed into the ethanol than would occur in a very humid climate.  

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ct9000   

Thanks for the discussion re ethanol. Here in AUS we have e10 available sold as about 96 octane and it cheaper to buy, in practice you find that you use up to 10% more of it and so negate the cheaper price. We use what is called premium unleaded sold as either 95 or 98 octane. these octane numbers refer to RON so is a higher number than MON. Our standard unleaded is 91-91 RON and is ok for Rotax 80 hp. but not for 100 hp. Also available in some places is e85 but I don't know anyone dopey enough to buy it. To test for ethanol it is easy in the field just draw a sample in a jar add a small amount of water shake gently wait a minute, if fuel has ethanol the water will be absorbed and if no ethanol the water will separate out. Because water is heavier it will sink to the bottom fairly quickly. 

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Adam   
On 9/14/2017 at 7:04 PM, ct9000 said:

Interested to hear why you would use fuel with ethanol in it ? . Ethanol absorbs water and therefore promotes corrosion also is more likely to suffer from freezing problems. You also use more of it - more fuel per hour. I acknowledge that Rotax will tolerate 10 % ethanol but I would not use any fuel with ethanol in it at any price. 

Ed and I live in California.  You cannot buy gas in this state that does not have ethanol in it.  Our two options are 91 octane premium with up to 10% etanol (we also dont have 93 octane) or 100LL.

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ct9000   
27 minutes ago, Adam said:

Ed and I live in California.  You cannot buy gas in this state that does not have ethanol in it.  Our two options are 91 octane premium with up to 10% etanol (we also dont have 93 octane) or 100LL.

It looks like governments all over the place are forcing their will on us.

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1 hour ago, ct9000 said:

It looks like governments all over the place are forcing their will on us.

Feels like its the corn farmers forcing their will by using government.

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11 hours ago, Ed Cesnalis said:

Feels like its the corn farmers forcing their will by using government.

That's closer to what's happening.  Ethanol is a loser in terms of energy production, it takes something like 1.2 BTU of energy to produce 1 BTU of energy from ethanol.  It literally costs more energy than you get from it.  But the agricultural lobby is very strong in Congress, and the federal 10% ethanol mandate provides a very steady, strong revenue stream for the farmers.  Much more so than corn used for food and animal feed, which has more seasonal swings.  

That's also one of the reasons for the proliferation of High Fructose CORN syrup over sugar in foods.  Sugar is literally dirt cheap, but we'd have to buy most of it from foreign suppliers like Brazil.  Congress would rather force us to higher rates of Diabetes using corn syrup produced in the good 'ol USA, so they slap huge tariffs or outright bans on foreign sugar imports.

Not trying to turn this thread political, just an aside on the ethanol thing since it affects us as pilots and fuel (and food) consumers.

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2 hours ago, FlyingMonkey said:

Congress would rather force us to higher rates of Diabetes using corn syrup produced in the good 'ol USA, so they slap huge tariffs or outright bans on foreign sugar imports.

Congress can't (currently) force me.  I don't eat plants.

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Adam   

God Bless Mexican Coke with good old fashioned sugarcane!  Can't get ethanol free gas in CA, or 93 octane but I can get Mexican Coke at Target!

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Anybody else add like 15% 100LL to there Mogas? I have a 100 gallon tank WITH pump in the back of an old pickup that I leave in my hanger. When it's empty I put 15 gallons of 100LL in the tank then drive the 2 miles to the station and fill er up with 91 octane with NO Ethanol. I just like to make sure there is no chance of detonation, so I add that 15% aviation 100LL to be sure. I'm flying 2 or 3 times a week so the 100 gallons never gets stale. 

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12 hours ago, Adam said:

God Bless Mexican Coke with good old fashioned sugarcane!  Can't get ethanol free gas in CA, or 93 octane but I can get Mexican Coke at Target!

 

That is the good stuff (if such a thing is possible with soda pop!).  You can also try "Dublin" Dr. Pepper.  Dublin, TX was the original Dr. Pepper bottling location, and that is the only place that still uses cane sugar in making DP.  If you can find it, it's a real treat and tastes worlds better than DP made with corn syrup.

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On 9/18/2017 at 10:53 PM, Scrapman1959 said:

Anybody else add like 15% 100LL to there Mogas? I have a 100 gallon tank WITH pump in the back of an old pickup that I leave in my hanger. When it's empty I put 15 gallons of 100LL in the tank then drive the 2 miles to the station and fill er up with 91 octane with NO Ethanol. I just like to make sure there is no chance of detonation, so I add that 15% aviation 100LL to be sure. I'm flying 2 or 3 times a week so the 100 gallons never gets stale. 

If you can get 91 no ethanol gas, I'd use that straight.  The "minimum" 91 octane spec is certainly already conservative, and should be fine.  Introducing even a little lead into the fuel is probably more detrimental than any risk of detonation at 91 octane, IMO.  I have run 91 octane no ethanol before on long, hot cross-country flights and had zero issues.  

Since I can only get 90 here with no ethanol, I have considered cutting it with 100LL.  But Roger has insisted here quite a bit that lead is worse than ethanol for these airplanes, so I just use the 93 with ethanol instead of dealing with the mixing hassle.  But either answer is probably fine.

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Not sure if I will keep doing the same for the 914 in the new Tecnam? I'm guessing it calls for about the same octane etc, even though it's a low compression engine, and you would think could burn a lower octane gas? I haven't researched it at all yet? 

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