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Ethanol and Gelling - chemist's opinion solicited

Recently we’ve had in some threads comments on ethanol seperating out and gelling. I’ve made posts with this referral myself, specifically with regard to gas sitting a long time in the tank of a Chevy Volt. Literature suggests that happens in a matter of weeks. One poster suggested that gelled ethanol would remix with the gasoline via agitation.

I’ve looked for information on whether gelled ethanol will break down and remix with agitation, but have been unable to find anything on this issue. Does anyone out there (perhaps a chemist among us) have any real info on this? To my mind this will become an important issue when ultra-high-mileage hybrids such as the Volt hit the roads…and the repair shops.


Why would ethanol, even if it separated out of the mixture, turn to a gel? I thought ethanol was a liquid.

It is. But according to the Mobile website as well as other sites I’ve visited it will seperate out and turn gelatinous. Seeing as how it’s a distillate rather than a refined petroleum product, it apparently ages differently. It’s causing problems in boats and small engines (such as constuction tools) due to this characteristic.

I’ve read this but don’t understand the chemistry. I’m wondering its relationship to problems that we’re seeing posted and if this will be a more serious problem with gas sitting in Chevy Volt gastanks.

Some educated guesses on my part - a little water creates the separation, then some bacteria makes it gel. We can’t be the only creatures that like ethanol!

Interesting theory. Would that make it averse to remixing with the gas if agitated?

As I think this through more questions are coming to mind…is it heavier or lighter than gas? If it’s heavier, doesn’t breakdown with agitation, and collects at the tank’s bottom, will we see cars like the Volt with ethanol blobs at the bottom of the tank? If it’s lighter, will it drop down as the gas gets pumped out and clog the pickup acreen when it gets to that level?

I’ve tried some internet research, but have been unable to find this type of information. Perhaps the effects of ethanol in the scenerio of cars in storage and hypermile cars has yet to be explored. Perhaps the assumption is thatt it’ll stay homogenized into the gas, which for normal situations (daily drivers) it does.

Ethanol won’t gel on it’s own. It needs a gelling hydrocolloid such a carpobol-series or a polysorbate-series gelling agent. If ethanol is gelling in fuel tanks, then there’s something else in the fuel that’s causing it to gel.

The only thing I’ve seen with ethanol blended gasoline that’s been stored over an extended period of time is the phase seperation of the ethanol, along with any moisture out of the gasoline. Never any gelling.


Thanks for posting.

Since hydrocolloids are colloids dispersed in water, and since colloids are extracted from plants as is ethanol, could they not be normally present in small amounts in ethanol? If the hydrocolloids phase seperate into colloids and water, could they not gel?

Bear with me please. I’m not being argumentative, I’ve just trying to resolve the info to better understand the issue. Chemistry is not my forte.

That could happen. But that would mean that whoever is distilling the ethanol is doing a lousy job of it, or their distilation equipment hasn’t been maintained properly.

Even when making moonshine, the still has to be taken apart and cleaned on occation.


Cool. My perception was apparently in error then.

Thanks for posting. I’ve learned something today. It’s a good day.

I didn’t pay much attention to gelling, just separation in the other thread. And my 2.5 gallons of gas for the lawn mower lasts a couple of months. I’ve never noticed gelling. It seems that it would float or sink to the bottom of the gas tank. I’d see it in the mower tank, since it empties almost completely after each mowing.