Does Ethanol speed up rubber breakdown?

[chep]

The other day I diagnosed a friends Stihl 270 with a leaky fuel line, it had 1/4-1/2 inch cracks up and down it. He went to the local saw shop and the man behind the counter told him that it was a growing problem. He said that with higher Ethanol ratios in our fuel (up to 10% here)that fuel is breaking down rubber quicker than before.Has anyone even heard of this? Can you either verify this, or claim the same problem?

 

[Eric_E]

A saw shop I go to claims the same thing.

 

[treegazer]

Because it's true.

 

[Keith]

The manual for my 9 year old Stihl 025 warns of using fuel with additives which degrade elastomers (carburetor diaphragms, oil seals, fuel lines, etc.).

It is still possible to find high octane fuel with no ethanol, but it isn't easy.

 

[treehumper]

Ethanol is a solvent and breaksdown rubber and makes mush out of fiberglass. There are a number of websites that discuss this issue. It's prevelant in outboard motors because of the time the gas sits and the chance to mix with water vapors in the tank. When fuel sits the ethanol separates out and mixes with the water forming a sludge that will clog apetures in the fuel system causing the motor to sputter and stop.

I checked with my small engine mechanic and he verified the problem. The solution is premium gas from the major distributors since there is usually no ethanol in it.

 

[Jamin_Mayer]

So, am I crazy using 91 octane in my saws?

Dang.

 

[treehumper]

NO. You want high octane since it usually contains no ethanol. But check at the pump or with the owner/operator to confirm this.

 

[Jamin_Mayer]

Oh. I got it now. I'll have to check.

 

[ChuckR]

My understanding is that nearly all regular AND hi-octane gas is oxygenated. You have to look pretty hard to find gas that isn't.

 

[treehumper]

mix in a stabilizer and get a finer filter for the gas tank. Talk to your mechanic about that. Don't bulk store gas for too long that's where many of the problems arise. The alcohol settles out from the gas and can mix with water in the tank as well as eat the rubber.