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Author Topic:   Ethanol Effect on Aluminum Fuel Tanks
msirof2001 posted 04-23-2015 01:41 PM ET (US)   Profile for msirof2001   Send Email to msirof2001  
My 1995 Outrage 21 has a 122-gallon aluminum fuel tank. What effect does ethanol E10 or E15 have on this type of tank? I heard it had an effect on plastic tanks; I wasn't sure about aluminum. I appreciate any thoughts from those with knowledge or experience with this.
jimh posted 04-24-2015 02:37 AM ET (US)     Profile for jimh  Send Email to jimh     
Gasoline fuels made from blends of ethanol and gasoline in a 1:9 ratio have been in common use in my state (Michigan) for decades. Since 1987 almost all rubber fuel hose for use on boats has been marked as being alcohol-resistant and has been able to tolerate ethanol-gasoline blended fuel (at 1:9 mix)--at least the better grades of rubber fuel hose. (There are always some inferior grades of anything.)

Aluminum is not bothered much by gasoline or ethanol-gasoline blended fuels that I have seen. There seems to be more concern about water in the fuel tank.

There is one particularly frequent mention of a possible problem with ethanol-gasoline blended fuels: if there is too much water present, the ethanol can come out of solution with the gasoline and go into solution with the water. Some have made claims--I don't know any real basis for these but I am just repeating the claims--that a solution of water and ethanol is harmful. I don't know if that is true. It has been claimed to be true, but I have never seen any good authority cited to confirm it.

It does not seem very intuitive to me that alcohol and water would form a solution that was more harmful than either pure alcohol or pure water.

My boat has an aluminum fuel tank made in 1992. It is thus 23-years old. I have owned the boat for about ten years. During the last ten years the fuel in the tank has been mostly ethanol-gasoline blended fuel. I have not observed any harmful effects.

I would not use ethanol-gasoline blended fuel above a 1:9 mix. A mix of 1:7 would be too much ethanol for me.

jimh posted 04-24-2015 02:43 AM ET (US)     Profile for jimh  Send Email to jimh     
Read post #11 in this thread:

The author says he is a chemist. His comments on the corrosive effects of alcohol on aluminum are in diametric opposition to the claims I mentioned above. According to that chemist, alcohol in water is less corrosive than just alcohol.

jimh posted 04-24-2015 02:48 AM ET (US)     Profile for jimh  Send Email to jimh     
Here is another interesting article:

It separates Ethanol and Methanol. And ferrous and non-ferrous metals.

And one more:

It says the harm comes from bacteria that might grow in the ethanol fuel.

msirof2001 posted 04-24-2015 12:16 PM ET (US)     Profile for msirof2001  Send Email to msirof2001     
JimH- Thanks for all of this information and for the links. Your personal experience is reassuring. A friend of mine had to replace the fuel tank in his ten year old Robalo. His fuel tank replacement was not directly caused by ethanol, but I saw that he spent thousands in cutting the deck, replacing the tank, and then attempting to re-finish the deck to look like it had never happened. His experience got me thinking about all of the potential causes of a fuel tank replacement, including the impact of ethanol. Hence my original post. Fortunately, if a fuel tank replacement is required, Botson Whaler was insightful enough to engineer a removable deck. My impact would be a lot less than his. He is now getting cracks in the deck where the work was done. Your information was insightful.
dfmcintyre posted 04-24-2015 05:40 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
I think one critical issue is not the amount of fuel, but the use of the vessel; how much is it being used. Again, just my observations with our 30' Chris Craft. Not a problem until my father started not taking it out (health reasons). A lot of sitting at the dock, I feel contributed to the degradation of the fiberglass tank, to the point where there was an observerable line in the tank where the resin had started to degrade. Not the glass, just the resin. Long, 1/4 - 1/2" tendrils of resin were observable in the bottom of the tank, and hanging off the tank roof.

Any of you hesitating due to the cost and problems, well, we've got you beat. $6000 to remove, design, fabricate and install.

Regards - Don

jimh posted 04-25-2015 11:01 AM ET (US)     Profile for jimh  Send Email to jimh     
My impression of fiberglass fuel tanks or other plastic resin laminated fuel tanks is they are not suitable to be used with ethanol-gasoline fuels. There seems to be a very real problem and concern about ethanol-gasoline fuels affecting the resins used in fiberglass laminated fuel tanks.

A good example of the unsuitability of fiberglass fuel tanks is seen in the experience of PATE PLASTICS. They made fiberglass fuel tanks for many years, but once ethanol-gasoline fuel came into use their fuel tanks began to exhibit failures.

A few years ago I searched for other manufacturers of fiberglass fuel tanks. The ones I found were in the aircraft business. In aircraft there is a prohibition of use of any ethanol-gasoline blended fuels, so aircraft do not have a problem with fiberglass tanks.

jimh posted 04-25-2015 04:43 PM ET (US)     Profile for jimh  Send Email to jimh     
In a prior discussion, I give several hyperlinks to a lengthy first-hand account of the recent experience of a boater with a fiberglass laminated fuel tank and its unsuitability for use with ethanol-gasoline blended fuels. The prior discussion is eight years old, and, quite handily, all the hyperlinks I gave appear to still be working. See

White Bear posted 04-28-2015 02:07 PM ET (US)     Profile for White Bear  Send Email to White Bear     
No effect on the aluminum tank, but it may very well clean prior accumulations from the tank walls resulting in clogged fuel filters.

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