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Boating All Out

In article ,
says...

On Sat, 27 Apr 2013 15:02:52 -0500, Boating All Out
wrote:

Or keep the tank topped off
when idle for long periods.

Why topped off? Ethanol will phase separate no matter how full the
tank is. You just start the season with a whole tank of bad gas.

Phase separation can only occur when the ethanol reaches its water
saturation point. So you've basically got water in your gas.
With no ethanol the water still separates, sinking to low spots.
But quicker and probably worse in terms of corrosion.
Ethanol will keep water in suspension until saturation.
Even when phase separated the water is held in suspension by the
ethanol. I don't know the corrosion effects of that mix, but it easy to
guess it depends on the materials, and might be less than pure water.
The key is to keep water out of the gas. Assuming you didn't buy
watered gas, it gets in the vented gas tank by condensation out of air
onto the tanks sides, and maybe the gas surface itself.
No air in tank, no condensation. I wouldn't even worry about keeping a
non-vented gas storage jug topped off, unless I lived in a highly humid
area. In fact, I don't worry about gas in vented tanks until it's about
a full 2 years old. Not because of water or "phase separation" either.
The volatiles are lost and it's poor starting/running gas.
The only knock I have with ethanol's use as an oxygenator is the real
possibility of it hiding wet gas, because it can suspend water in the
gas. If not too much the water just gets vaporized in the combustion
chamber.
It used to be cars would stall when there was water in the gas, and
service station tanks were carefully monitored for ANY water.
Now, more of that 4 bucks a gallon you're paying for gas might be for
water.