does Stabil work?

72bluNblu said
Yes, ethanol does absorb water. But the amount of water it can and will absorb under certain conditions is limited. If you have 15 gallons of air space in your fuel tank, you have 15 gallons of air with moisture in it to condense when the temperature changes. And since it's vented it gets to replenish that moisture after it condenses out and drips into the fuel. The larger the air volume in the tank, the larger the amount of moisture than can be condensed. And the more surface are for condensation to form on. That doesn't just get absorbed, it's enough water to just sit in the bottom of the tank if you leave it long enough.

Yes, you will have fuel evaporate so your tank will not remain 100% full. But back to my first point, the more air in the tank, the more moisture in the tank. Having a full tank of fuel and then having a 1/2" of fuel evaporate off the top leaves a very limited amount of air, and therefore less moisture. Having an empty tank with a couple gallons of fuel in it means it's actually full of moisture and not fuel.

As for the "myth", you can "bust" it yourself. Park your car outside for a couple days with a 1/4 tank of fuel when the temperatures go below the dew point. Take an inspection camera and run it into the tank before it warms up for the day. You will see all the water dripping off the inside top of the tank. Leave it out there for a winter and when you run that camera in you'll see all the condensation AND all the flash rust above the fuel line. Yeah, I've done it, and I've seen plenty of tanks that way with an easily recognizable rust line that corresponded with the fuel level. I'd rather drain a tank of old fuel than replace a scaly fuel tank. Middle of winter isn't actually the worst, fall and spring are the worst because of the large temperature swings.

My cars have pretty much always been parked outside since before I even had a license, so, let's call that almost 30 years now. Car rich and shop poor. Always left the tanks full on anything that was going to sit for awhile, never used Stabile or anything else. So I moved in '21 and during the early part of that process my Duster's wire harness finally quit so it spent the '21/22 winter outside with a burnt up wire harness and a full tank of fuel (because I filled it). It got rained on, snowed on, all of it. It sat for more than 6 months, because again, I had to rewire the whole car and I had to wait until spring to do it, so I couldn't even start the poor girl. Fired right up, ran fine, even with all the crazy stuff that goes in the fuel here in California. Did it run better after I cycled a tank of fuel through it? Of course. But I didn't drain the fuel and start over either, and the tank is still nice and clean inside.

This was my Duster that winter (yes, I cleared all the snow after the picture).

So no, condensation is not a smaller problem than fuel destabilizing. At least not in my experience, and yeah, I probably get the most ethanol and other additives of anybody since I'm in California. Always left the tanks full, never used any fuel stabilizer, never really had an issue. If they sit longer than 6 months or so the idle gets a little funky, but that's the worst I've had.

And lawn equipment you just run the tank bone dry, same with the carb. It's better that way than full, but lawn equipment is easy to drain and easy to refill. And there's no long fuel lines to rust, or tanks, or anything else since all that stuff has a plastic tank that goes near direct gravity feed to the carb. Completely different scenario.

See, this is the thing, its way overblown on that, I don't know how many cars are stored outside with snow on them, or how close you are to the ocean, but it's damp here in Michigan a lot of the year, and you have to let it sit a long time to even get enough water in there to matter.

The other thing is that the ethanol molecules that are suspended in the gas will sette to the bottom when they absorb enough water for phase seperation, so the lighter gasoline will continue to rise to the top, and it will continue to contaminate. But you need a lot of water for that. Like I said this gets parked 5' away from a car driven in all weather, all year.

It just got cold here in Michigan, big temp drop, heavy dew on the yard every day for weeks, several days of dripping wet.

Just for your entertainment, I got a picture of the inside of the 53+ year old filler neck (with 30 years in Jacksonville, FL) and the 8 year old spectra tank that's always been stored 1/4 or less full with the endoscope (which doesn't have a great light as you can see). There's basically no rust in the neck and none at all in the tank. Even that sending unit is the original 53 year old one for the car. Car hasn't moved for over a week and the gas is about a month old already. 93 Octane E10.

Point being: 6 months indoors? Don't worry about it at all. Covers most of us.