The majority of gasoline in the United States is currently E10 or E15, meaning it is 10-15% ethanol–the same type of alcohol found in your liquor cabinet. Modern engines are engineered to work efficiently with this fuel. In the majority of cases E10 will not hurt your car, but there have been studies that show evidence to the contrary.
Moisture/Separation
The biggest issue with fuel containing any amount of ethanol is moisture. Ethanol draws moisture more readily than gasoline, so the higher the content the more moisture that can be drawn. When a certain amount of moisture is mixed with ethanol, it will actually separate from gasoline, during the fuel into a gummy mess that cannot be burned in an internal combustion engine. The moisture can be gathered at any point of the transportation process: in the storage tank at a refinery all the way to your fuel tank. Granted, this rarely happens, but it can be a concern if you start using E15 or if the EPA starts approving a higher concentration of ethanol.
Caution with Pre-2000 Models
Above, we said that E10 would not hurt your car in most cases. That assertion assumed that you have a fairly recent model, say something from this century at least. Older models, pre-2000, cannot handle E10 as well. Many older fuel system components are unable to stand up to the corrosive effects of alcohol, causing considerable damage to some components.
Study Links Valve Damage to Ethanol
One study dispels the safety of ethanol fuels altogether. In 2012 Auto Alliance released a study showing that some cars from the model years 2001 to 2009 had engine damage that could be linked directly to the use of an ethanol fuel blend. The damage was extensive and affected the valves and valve seats. One of the cars in the study even failed emissions compliance standards. The repairs to bring the vehicle back into compliance would have cost more than the vehicle’s value.
Congress is considering making E15 the standard fuel at the pumps. The Auto Alliance study showed that to be a bad idea. The study indicated that cars running on E15 are less fuel efficient than those running on E10, defeating the purpose of diluting the fuel in the first place.
