E10 Ethanol Gas During Long-Term Storage

This is a look at at the effect of storing unstabilized E10 gasoline for a prolonged period of time.  Up front though, E10 gasoline does not appear to phase separate over time, or require additives for stabilization, if used and/or stored during normal seasonal riding.  Further, the ethanol content of E10 gasoline does not drop out of the gas mixture if stored for a prolonged period of time, i.e. 2 years, unless a large amount of additional water is added to the E10 gasoline artifically.  E10 stored for these comparisons did not show any noticeable degradation from being stored in high humidity locations.  The best thing for putting a XR1200 away for the season therefore still seems to be to simply fill the fuel tank with fresh gasoline to keep out condensation and to cover the fuel pump internals; and, to change the oil, cover the bike, and put it to bed with a battery tender.
 
If, however, there is any suspiscion that a significant amount of moisture/water has already gotten into the fuel tank, then before winter storage the best thing to do would be to remove the tank and completely empty the bad fuel/water, fill the bike with non-ethanol 93 octane fuel (available at many race tracks and boating marinas), run the tank almost empty, then re-fill with good gas and ride it normally, or store it for the season.
 
As far as I can see, there is no information which suggests that use of E10 gas contributes to fuel tank swelling or other engine problems on the XR1200.  I have noticed sweilling of o-rings, seals, etc. when running non-ethanol race fuel - but the swelling goes back down when returning to use of ethanol pump gas.  Therefore, any fuel tank or system swelling may be attributable to other fuel additives in an area, but not to ethanol content of the E10 fuel.
 

Fuel Testing
 
Observations for these comments are based on over two years of testing of E10 pump gas stored in a variety of plastic and gas containers.  To be comprehensive I looked at E10 gasoline in octanes from 87 through 93.  I also took gas samples from 8 gas stations within my geographic area.  4 in the suburban Washington, DC area, and 4 from suburbs about 30 miles south of Washington, DC.
 
While I do not have a laboratory, I did use an ethanol/phase separation test kit  (see other pages for test info) to confirm observations.  Over two years of random testing on fresh and stored E10 gasoline, I have not noted phase separation of E10 ethanol gas in any case.  Unless induced by adding large quantities of water to the gasoline, the E10 gas which I have been monitoring has not phase separated during extended storage.  That means that the ethanol added to the E10 gasoline stays in suspension unless artifically caused to separate.  And, I have not observed any issue with ethanol, water, or varnish-like substances separating from E10 gas during 2 years of focused observation and apprximately 10 years of E10 gas usage.
 
On the other hand, I do regularly run non-ethanol race gas (VP Racing) in one of my motorcycles (not the XR1200) and have tried octane boosting additives in the gas used in the XR1200 and other motorcycles.  In all cases in which I have used non-ethanol race gas in other late model Harleys with metal gas tanks, the rubber o-rings in the fuel filler cap have swollen and would not properly seat.  The cure has been easy, but requires removing the o-rings from the non-ethanol gas and allowing them to dry in open air for a day.  Use of E10 gas does not cause this problem. 
 
Likewise, use of octane boosting additives in the XR1200 has also caused the o-ring in the gas filler cap to swell and no longer fit properly in the filler cap opening.  Again, air drying the o-rings and removing the gas with additive from the motorcycle has cured this problem.
 
Ultimately, E10 gasoline has never caused any problems in my XR1200, its plastic gas tank, or any other Harley that I have run it in.  Also, storing late model EFI Harleys with full tanks of E10 gasoline for the winter - without additives - has never causeda problem with the fuel system.  Having sent fuel injectors to Marren Fuel Injection (www.injector.com) for cleaning, after several years of use and storage with E10 gas, no instance of fouling or gummng has been noted.  On the other hand, non-ethanol race fuel and fuel additives for E10 gas have caused swelling in rubber parts in the fuel tanks of Harleys in which I have used it.
 
 
E10 Fuel Samples
 
 
Here is a look at E10 gasoline that had been stored for about a year and a half in plastic bottles.  (This is a representative set of samples from numerous E10 samples of different age and octane, which I have collected.)
 
The four samples below were drawn in June of 2010 and stored in those plastic bottles in a garage were temperature varied from about 15 deg F to 100 deg F.  Humidity ranged into the high 90% region.  These samples represent one bottle each of 87, 89, 91, and 93 octane gas from the same Sunoco station drawn on June 18, 2010.
 

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Four Samples of E10 Gas
 
Separately, I tested the ethanol level of those samples at the time that I obtained them as noted at this link.  I subsequently tested them approximately 14 months later as noted below to determine how the ethanol content was affected by prolonged storage in porous plastic containers.  I have conducted other testing and observations on my collection of gas samples.
 

 
Testing of E10 Gasoline Stored for a Prolonged Period
 
Looking closer at one of the above samples - a bottle of 93 octane E10 gas - there was no indication that this gas had separated in any way after over a year of storage. Visually it can be seen that it has not separated in terms of the alcohol mixture.  If it had separated there would be visible layers of gasoline, and alcohol/water in the bottle.
 

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93 octane
 

The following two pictures are a closer look at the top and bottom layers of the gas in the bottle.  Again, there is no obvious separation at these layers.  (The shadow in the bottom of the botle is the slight hollow moulded into the plastic.)
 

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Top Layer

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Bottom Layer
 
Although it can be seen in the above pictures that the gas has no visible separation, to get an even better view I transferred the E10 gas sample over to the glass cylinder seen in the following picture.  It was difficult to get a clear picture without shadows or distortion from the curved glass, but again, the sample does not show separated layers which would be evident if the ethanol has phase separated. 
 

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Gas in Beaker
 

But just to clearly show that there has not been any phase separation, the following picture shows the E10 gas with an ethanol testing marker dye added. 
 
If the dye stays evenly in suspension, then the ethanol has remained evenly mixed in the E10 gas as intended.  The dye will have nothing to bond to in non-ethanol fuel and will fall cleanly to the bottom of the gas if the gas does not contain ethanol. 
 
If the ethanol has phase separated from the gasoline, then the gas will not turn blue - but the ethanol and any water which might be in the fuel, will be colored blue and will settle to the bottom of the container. 
 
The following picture shows the dye added to the sample...
 

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Gas with Marking Dye
 
Mixing the E10 gas with the added dye, it can be seen that the alcohol has not separated from the gas.  The dye is evenly mixed through the gas and does not show any separated layers.
 
For comparison, to show what the separated ethanol would look like, the below picture shows the above gas sample after I have forced phase separation of the E10 gas by addition of liquid water.

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Phase Separated Gas
 
In the above picture one can clearly see the separated layers of gasoline and alcohol/water which will be visible if ethanol phase separates from E10 gas.  Here the ethanol, and the added water which was used for phase separation, have settled to the bottom of the beaker.  The blue dye stays with the water/ethanol that has dropped out of the gasoline.  (Since I rushed the photograph the gas is still slightly cloudy, but after a few more minutes the remaining ethanol/water suspended in the gas would settle out and the gas in the top layer would be clearer.)  It is possible to see the separated layers without the blue dye, but it helps in these photographs.  This separated gas would clearly make a mess of a fuel system.  But, this only happened after I forced the separation by pouring in additional water and stirring, and not from storage over a prolonged period of time.
 

Conclusion
 
I know that people do not like the idea of E10 gas, but the point to be made here is that E10 gas will not generally separate simply due to prolonged storage.  E10 gas will separate if a substantial amount of liquid water is added to it (and therefore is not ideal for boating or aviation).  However, if one takes just the minimal amount of caution in filling a motorcycle fuel tank and keeps the filler cover in place so that liquid water is not added to the fuel, there is no reason that E10 gas should separate when used in the XR1200.
 
I have never had any problem with leaving unstabilized E10 gas in motorcycles stored for a year or more at a time.  (Or in EFI cars stored for several years at a time.) And, the fuel injectors from motorcycles stored like this have not shown any significant blockage or gumming when sent to Marren for cleaning and blueprinting after extended use and storage.
 
While storing motorcycles (and cars) with full tanks of E10 gas has not caused me any issues, non-ethanol race gas has caused rubber o-rings in the fuel systems of my motorcycles to swell.  Swelling has gone down after the race fuel is removed and these parts are allowed to dry out.
 
Also, the use of octane boosting additives for E10 gas has caused similar problems in Harleys (including the XR1200) in which I have used it.  Swelling has likewise gone down after the additives were removed and the parts have dried out.

So, while other fuel additives, including those regionally mixed into fuels by manufacturers, may cause fuel tank/component swelling, it is not indicated that the ethanol content of gasoline is the problem.

 

 
 
 

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