Some time ago I indicated that I would post pictures of a long term fuel test on a sample of ethanol blended gasoline (also called E10). A little background is necessary. Those who frequent this forum know that I am not particularly concerned about E10 fuel as in my area (Minnesota) we've used the stuff since 1997. I personally have seen none of the devastation that others have either read about or personally observed but I do understand that there are some issues in coastal areas. I will present three pictures of the fuel sample with a bit of description of what you are looking at, followed by a recommendation and from there you can draw your own conclusions.
Picture #1: The sample.
This is a sample of "untreated" E10 (in a 12 oz soda bottle) that dates to August 6, 2009. It has been in this container (vented) since that time and has undergone a 130 degree temperature swing along with the associated humidity changes. This fuel was stored outside for three of the six months and in my garage the last three months. At first glance you would think the brown stuff at the top looks awful. Actually that brown color is the very top of the fuel level as the camera is looking upward through the liquid column. It is of no consequence whatsoever. It is the dark color at the bottom of the container that we will be discussing.
Picture #2: A close up
This and the other pictures were taken looking upward throught the container, with the container tilted toward the camera. This moved the separation into one of the indentations at the bottom of the container. The discoloration on the other areas of the container represent merely trace amounts and are also of no consequence. The amount of separation in the indentation facing you would in my view, amount to the displacement of perhaps a nickel and that might be a stretch.
Picture #3: Moisture content
If you look at the indentation at the right you can see very small bubbles of moisture. There is no actual moisture (an actual layer of water) in this sample except for what you see.
This is certainly not a scientific experiment but it reinforces my feelings that 6-month old E10, even untreated will not generally cause any runability problems. I poured the contents of this test into my snowblower. My suggestion for E10 users is this: Use a fuel system treatment like Stabil Marine, SeaFoam or any of the engine manufacturers fuel treatments and go boating. If you have an older motor and are just switching to E10, clean the fuel tank, change the fuel lines, change the fuel filter, and go boating. If the engine does begin to act up, do not continue to run it that way. Chances are the carb(s) and the fuel pump now need rebuilding with ethanol tolerant components. The engine itself doesn't care about E10. If you live in a coastal area or have a very large boat with extremely large fuel tanks but don't use large amounts of fuel you may want to implement additional moisture protection measures.
