Winter Storage

svt2205 · Post by **svt2205** » Sun Oct 12, 2008 5:34 am

Unfortunately it's approaching that time a year again and I'd like to know if anyone is changing their winter storage habits because of the now common 10% ethanol that's in our gas. I've read that E10 can go thru a phase change where the gas and water separates. Once this occurs, you're screwed.

I'm debating if I will run my tank dry for the winter. I still need/want to change my fuel pump and that would surely simplify things, but it's mighty cold with an unheated garage.

Thanks

phorty · Post by **phorty** » Tue Oct 14, 2008 2:26 pm

I don't have any answers for you but I'm subscribing to the discussion...

svt2205 · Post by **svt2205** » Mon Oct 20, 2008 3:38 am

I think this is the solution

http://www.goldeagle.com/sta-bil/stabil_marine.htm

Black306 · Post by **Black306** » Mon Oct 20, 2008 8:25 pm

svt2205 wrote:I think this is the solution

http://www.goldeagle.com/sta-bil/stabil_marine.htm

Good to know. I'll pick up a bottle of that stuff when I run out of regular Sta-bil

Dantak · Post by **Dantak** » Tue Oct 21, 2008 1:11 pm

Well, I don't have the answer, but I'm a chemist so here are my two cents
What you mean "phase change", is phase separation, which is a misnomer. The "phase" is still liquid and there is always gaseous fuel in your fuel tank. Phase in this case doesn't really refer to state of matter. What they mean here is the difference between the aqueous and organic phase. Typically they are very different (i.e. oil and water). But this is not the case with ethanol. Short carbon chain alcohols are soluble in water because the polarity of the OH group overcomes hydrophobic ($10 word) nature of the carbon chain. What this means is that the ethanol is going to try to dissolve water which is insoluble in petroleum (a hodgepodge of totally organic hydrocarbons). And thus, the ethanol/water layer will separate from the purely organic petroleum layer. The assumption is that while gaseous water in your tank would typically be repulsed by the fuel, the gaseous ethanol would hang out with the water and eventually condense in the fuel. This supposes that there is a significant amount of water vapor in your fuel tank, which presumably, there isn't, and that a significant portion of that 10% ethanol is going to evaporate, AND join with the gaseous water, AND condense back into the fuel. While 10% EtOH seems significant, let me just point out that fuel is up to 1.5% oxygen and almost completely alkane (carbon chains without the alcohol group). So, it seems reasonable that all fuel contains some alcohol. Also, I would be very interested if "10%" means by volume, weight, or molecular weight. That would make a considerable difference in how much ethanol is actually in there.

okay, I'm done, sorry just couldn't resist.

Post by **1993cobra** » Tue Oct 21, 2008 2:04 pm

yeh! WHAT HE SAID!

Mike S. · Post by **Mike S.** » Tue Oct 21, 2008 6:49 pm

Yeah... uh... so, basically, drain the tank!

-MJS

Dantak · Post by **Dantak** » Wed Oct 22, 2008 9:19 am

Mike S. wrote:Yeah... uh... so, basically, drain the tank!

-MJS

hehe, um...no. If it were me and I was concerned about it, I would fill the tank just as full as I could get it. Presumably this phase separation only works with water vapor in the head space of the tank (we are assuming there isn't any water in the fuel). So if you completely fill the tank you only have to worry about the water in the empty space at the top which shouldn't be much.

svt2205 · Post by **svt2205** » Fri Oct 24, 2008 4:37 am

Wow... I wasn't all that concerned about getting the phase change vs phase separation terms correct. Didn't know this was going to be graded... he he.. But, thanks for filling in some blanks.

You do realize every fuel storage tank out there has water in it. So, you can't assume there's not water in your gas. I don't think you can fill your fuel tank so there's no head space, but not sure. But when storing a car you need to leave a little room in the tank for expansion. And this phase separation is a concern for those of us who use our cars on a very limited basis.

For me, I'd rather assume the conditions are right for the separation to happen.