I don't dump out the Avgas, but in the fall, I don't fill the bike's tank either.  Just a little dab will do ya, as the old saying goes.  Then I fill it in the spring with auto fuel, and off she goes.
My bike is a 2006 model, so I don't want to run it too much on the leaded fuel.

Well it has been a year since I started this test, and a lot has happened in the last few months.  Here is the cast:




E85 - The E85 was added to the test on 11-09-13.  It has changed very little in volume, there is no rust on the steel, the brass looks fine, and the aluminum has turned black with corrosion.





The regular pump gas has phase separation, a lot of the gas has evaporated, there is an orange jelly on the aluminum, the brass looks OK, and the steel is badly rusted.







The regular pump gas with the Star-Tron added has phase separation, a lot of the gas has evaporated, there is an orange jelly on the aluminum, the brass looks OK, and the steel is badly rusted.





The ethanol free 91+ gas from Country Mark Co-Op has no phase separation, some of the gas has evaporated, the aluminum, brass and steel look perfect.  The color appears a little more orange than it was a year ago.





The 94 Octane leaded Sunoco racing fuel has no phase separation, some of the gas has evaporated, the aluminum, brass and steel look perfect.





The 100LL Avgas has no phase separation, some of the gas has evaporated, the aluminum, brass look perfect....the steel has some surface rust on it.





What is the bottom line?

Pump gas with ethanol can begin to deteriorate in as little as 50 days.  You can use E10 in your bike safely...provided you use it enough to require a fill-up once a month.  The premium deteriorated in 50 days, the regular held up longer....maybe this proves the rumor that premium pump gas gets old sitting in the tanks at the gas station.

Adding Star-Tron seemed to delay the phase separation for a while - but it did not last a year.

I was surprised the Avgass 100LL allowed the steel to rust.....planes are in storage a lot and I did not expect this.

For me, I am going to store my Honda ST1100 with the ethanol free gasoline and a fuel stabilizer in the fuel tank, and drain the carb float bowls.  All the other bikes that are gravity fuel systems are going to be drained....both fuel tank and carbs.

Dave  

AWESOME information.  Great test, man.  You had rubber o-rings on the steel tubes, right?  Did any of them have any noticeable deterioration?

Blueish, greenish, reddish, yellowish, and white...
I believe we can paint... ...

Great effort on the test!...
I wonder in retrospect... how significant the integrity of the cap seal was...
Since our tanks are vented...
Then again,... nearly all the fuel might have evaporated if the caps had all been drilled to allow a small, intentional vent hole...
... but, I wonder if the difference in evaporation was effected by cap seal?...

Either way,.... I'm amazed at the obvious visual differences...
Thanks for taking the time, and letting us follow along... ...

For comparison...
Start...

End...

justin_o_guy2 wrote on 10/30/14 at 23:21:54:


I drilled a 1/16" hole in the caps to work as a tank vent.  The bottle were stored in my wood shed (metal carport) - so they were exposed to temperature and humidity changes, while no actual rain could get to the bottles.  This is the same way you would store your bike under a carport, or in a shed.

The O-rings I used are new ones, and I believe they are Nitrile.  Most likely resistant to fuel or ethanol.  I bought them to use in the petcock of my trials motorcycle, and was careful to buy something that held up to fuel....as the factory O-ring got soft when I used E-10 pump gas.

I had done this test a couple of years ago, and the caps were tight and the bottles were stored in my insulated and heated garage....and there was not any steel, brass or aluminum in the bottles.  I didn't learn anything from the test.  The pump gas did have some phase separation....but it didn't prove anything.

One interesting thing is that with the pump gas the steel only rusted in the "sludge" layer that formed at the bottom - while the Avgas 100LL allowed the steel to get some surface rust all over.  

Another thing I found interesting, is how the E10 pump gas evaporated so much more than the other gasoline types.  These fuels came from stations in the Cincinnati Metro area....and they most likely are "reformulated" fuels that are EPA mandated for to help clean up the local air quality.  The fuel was purchased in October 2013 - so I would imagine this is not the "summer" blend.

Well,NOW you're gonna hafta rerun the whole thing with Summer blend gas..
I can't BELIEVE you didn't cover THAT base, I mean, come On, man,  REALLY?


That was a really good test. That the steel rust line was on the line in the gas says a lot..
That the factory o-rings broke down in pump gas,, well, that says a,lot, too.

I did one more test this winter.  The Cincinnati and Northern Kentucky area (Boone, Kenton and Campbell Counties) are required to use Reformulated Fuel - while Pendleton County to our south is not.  Additionally - there is a Shell Station in Pendleton County that does not use Blender Pumps - so when I get Premium I am not buying a hose full of Regular before the Premium starts flowing.  I was curious if the Reformulated Fuel or the non-Reformulated fuel deteriorated faster - so I bought Regular and Premium from both stations and did another test.

I was surprised when the Premium from Pendleton County showed the phase separation first (not Reformulated)...maybe because they don't sell a lot of Premium down there and the fuel may sit in their tanks a long time....it showed phase separation in about 2 months.  The others caught up within a few weeks, and showed a little bit of ethanol settling out on the bottom.  (Even if you shake the bottles it does not go back into solution - which is an indication the ethanol has absorbed enough humidity from the air that it no longer mixes with the gasoline).







So what does this mean?  For me....it means that any equipment that is going to sit unused for more than a month....the fuel is drained.  This is applicable to anything that is in sheds, barns, under tarps...anything that is exposed to weather and temperature changes.  These bottles have a small vent hole drilled in the cap, and there were stored in my woodshed where no rain or snow could get to them....just temperature and humidity changes.