questions re: switching from ethanol to non-ethanol fuel

grady33

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My local marina (Ocean Pines) has switched to non-ethanol fuel. My tanks are full from the fall. Do I need to run the tanks dry before I switch to the non-ethanol fuel? The grady-white corporate site says not to mix the two. Why? Is a little mixing ok?
 

Curmudgeon

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I switch back and forth without issue, but run the tank down if that's what you want. The old problem was MTBE, which is supposed to have been phased out of straight fuel ... :wink:
 

magicalbill

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I have switched too, but mixed them as I never run my tank low.
Once I got all non-ethanol fuel, I no longer mix the two.
I had no problems either.
 

Doc Stressor

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The only way that you might have a problem is if the E10 in your tank has absorbed a lot of water. It can hold about 0.4% water in solution without separation. But the ability of different ethanol blends to hold water is not stoichiometric. That is, while 100 gallons of E10 might be able to hold 0.4 gallons of water, 200 gallons of E5 with the same amount of water can phase separate.

The safe thing to do is to burn most of the E10 before switching to straight gas.

That being said, I've switched back and forth a few times without any trouble.
 

grady33

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OK thanks. I will try and run the tank as dry as possible and then refill. Thanks again for the replies.