fuel shelf life in tank

[fried okra]

Is there a good rule of thumb as to how long ethanol free gas is still usable when contained in a Model A fuel tank?

In other words, how long would the fuel still be usable without having to drain the tank.

[Gene F]

I get various results when storing vehicles just for the winter. The first test is to smell the gas. If it is questionable maybe you can drain it off, and use it in something less critical like a lawn mower.

I will say this. When storing a car fill it up with premium fuel. Premium fuel does not break down as fast. Don't believe me, look at the owners manual for a Chevy Volt. Chevy Volts use premium fuel because that fuel may end up in that tank for some time, and GM does not want warranty repairs due to cruddy fuel when the gasoline engine has to run.

Old timers that want to cheap-out. The difference of 30 cents times lets say 9 gallons = $2.70. Not worth the trouble.

I started my wife's 1992 Corvette up in the pole barn the other day. Guess what, it runs terrible. She filled it up at season end, and she SAYS she used premium. Odd the last time this happened she put in 87 octane. That time it cost us a trip to the dealership... I even treated that fuel with stabil.

Like I said before, NOT WORTH THE TROUBLE.

[Ed in Maine]

I rebuild Zenith Carburetors using flow tested jets. I have found that after 2 years of ethanol use and storage by some of my fellow club members that the jets have reduced capacities of up to 5%. This can cause poor idle and lower high speeds and sticking float valves. I have often wondered, across the United States how many millions of dollars are wasted on premature repair of fuel handling parts due to ethanol. Ed

[Gene F]

Originally Posted by Ed in Maine

I rebuild Zenith Carburetors using flow tested jets. I have found that after 2 years of ethanol use and storage by some of my fellow club members that the jets have reduced capacities of up to 5%. This can cause poor idle and lower high speeds and sticking float valves. I have often wondered, across the United States how many millions of dollars are wasted on premature repair of fuel handling parts due to ethanol. Ed

Will treatment from time-to-time with products such as SeaFoam, or Gumout keep that from happening? 5% on these low HP engines can be a lit in the hill country.

[Synchro909]

IMO, these extremely low compression engine will run on fuel that a modern engine would not. I've had fuel in some of my Model As for up to 4 or 5 months and they started and ran just fine when I came back to them. No alcohol in the fuel I use.

[ronn]

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he stated ethanol free. a few yrs is no problem.

[updraught]

My sister has a Holden Volt, a re-badged Chevy, one of about 200 or so in this country.

"One problem with keeping the Volt fully charged for each day's commuting and shopping sorties from AC/mains power is that gums and solids begin to accumulate within the unused petrol, leading to the possibility of harder starting if or when the engine is required. Gibson explained to the media that the Volt comes with a pressurised petrol tank to extend the life of the petrol, but the car will eventually burn it off, to be replaced by fresh petrol.
[The Volt has] a pressurised gas tank, because we can't let anything get in and out of it, because the fuel will go stale very quickly. But after a year... [the engine] starts to burn the fuel off," explained Gibson.
Another compromise in an electric vehicle designed to operate on occasions with electrical energy supplied from a petrol engine is the need for the petrol engine to crank over once in a while to ensure moving parts remain lubricated"
https://www.carsales.com.au/editoria...al-guff-28094/

[1928Mik]

I'm with Gene F.... Luckily there is a farm store close that has non-ethanol and I use it plus either Sta-bil, MMO, Seafoam, or Gumout, whatever I have on the shelf at the time. I also remove the carb during the winter and spray it out with carb cleaner to get any build up of residue out. Never had an issue restarting after at least 6 months storage.

[jeepguy1948]

Ethanol free, premium, 1 oz per gallon Sea Foam. I have NEVER in 30 years had a problem, even up to storing 2 years. Worth every penny! Also, If it’s going to sit more than a month, after the gas valve is closed run the motor until it uses up all the fuel in the carb, use the choke to really suck up every bit of fuel. 1928’s idea of removing the carb and cleaning is a really good idea and something well worth doing if you live where your car will be parked for several months each winter. Fuel injected engines have less trouble because oxygen can’t get to the fuel once it’s in the system. If you cannot buy eth free in your area, you can do it yourself fairly easily, check it out on You Tube. In addition to the problems stated above, old fuel can cause starting problems. Maybe not (as Synchro say) in the low compression banger motor. But in lots of other motors. If old fuel is in the tank and the engine won't start, get it started with starting fluid (or your chemical of choice) and then it will run all day.

[jetrod]

I have had different results; We left 2 or 3 A's in the unheated garage in MI for 6 months while we did the snow bird thing- for 15 years. I did nothing but pull the fuse and go. Reg. pump gas, at what ever level they happened to be at and left. Returning, I just put in the fuse and started them up. NEVER ONCE did I have a fuel problem. Or a battery problem. JR

[rotorwrench]

Motor fuel with the common percentage of ethanol additive starts absorbing moisture anytime it is in connection with the atmosphere. How fast it absorbs the moisture depends on the relative humidity. If a person seals the fuel in a container then it will absorb very little moisture. The more absorption, the faster the deterioration rate. I live in a relatively humid area in south central Texas so the fuel gets stale at around the 6-month time frame. After a year, it already has a nasty varnish odor to it.

I've lived in cold climates before where the cold drops the relative humidity to very low levels. This would likely make it last for a longer period. I moved from the cold country long before they started using ethanol as an additive. We used to put HEET in the fuel to keep any moisture that might be in the tank from freezing and possibly blocking the fuel system. Down here in SA I don't think any additives would have been necessary back then. It doesn't freeze much down here.

[ronn]

Is there a good rule of thumb as to how long ethanol free gas is still usable when contained in a Model A fuel tank?


does anyone ever read the posts here? lol

[Tim Ayers]

Originally Posted by ronn

Is there a good rule of thumb as to how long ethanol free gas is still usable when contained in a Model A fuel tank?


does anyone ever read the posts here? lol

In theory, ethanol free gas should last a very long time.

Airplane fuel, though a different formula from automobile fuel, can last almost indefinitely. It is also ethanol free.

[rotorwrench]

I missed the alcohol free BUT, leaded AVGAS is not made from the same base stocks so it's expensive to produce. It's also illegal to use for road fuel. It is a paraffin base with low vapor pressure where MOGAS is based on aeromatic hydrocarbons that have higher volatility.

Avgas's chemical nature or low volatility makes it necessary to use TEL (tetraethyl lead) in order to achieve it's octane rating. It is very stable so it lasts a lot longer in storage

Mogas is more volatile so it needs no TEL to be detonation resistant. Alcohol free Mogas can be used under STC (supplemental type certificate) in some aircraft engines after blending with Avgas to reduce vapor pressure if it's too high. A person can't pull over up there if the engine fuel system gets vapor locked so vapor pressure testing is required for each batch.

The STC warns of storing Mogas to be used in the aircraft. Even with no ethanol, the high volatility fuels break down enough after 6-months that a person should avoid use of it in an aircraft engine application. It might be fine for automobile use at lest for a while longer.

[David in San Antonio]

I think avgas is available with lead in it. Please don’t use that version in your car.

[Tim Ayers]

Originally Posted by David in San Antonio

I think avgas is available with lead in it. Please don’t use that version in your car.

Why?

[David in San Antonio]

Why not use leaded avgas? Because the lead in the exhaust is a terrible poison.

https://youtu.be/6HlUm7dXq5s?si=Md4gWWizJj1R2JIx

[Tim Ayers]

Originally Posted by David in San Antonio

Why not use leaded avgas? Because the lead in the exhaust is a terrible poison.

https://youtu.be/6HlUm7dXq5s?si=Md4gWWizJj1R2JIx

I understand the issue with lead, but what reason not to use it as a fuel?

[updraught]

Originally Posted by Tim Ayers

I understand the issue with lead, but what reason not to use it as a fuel?

Because it is making Americans less and less intelligent it says.

[ronn]

Because it is making Americans less and less intelligent it says.



I can think of many other reasons for that diagnosis............


LOL

[nkaminar]

A little history may help. When cars first started burning gasoline it was more or less a single molecule. As more and more cars were built to burn gasoline, heaver molecules were mixed into the fuel. The octane rating suffered and compression ratios were reduced to compensate and the air/fuel going into the engine was heated to help vaporize the fuel. At this point storage was not a problem.

Now petroleum is cracked, which means the heaver molecules are broken down into lighter ones and the fuel is a mixture of many different molecules. Lighter molecules are there that vaporize easily to help the car start. The heavier molecules are there to fill out the fuel and make it cheaper to manufacture. The ethanol is there to also fill out the fuel and increase the octane rating.

What this means is that as the fuel ages, the volatile components evaporate leaving the heaver ones behind. These heaver molecules are really tar that can gum up the works. The ethanol attracts moisture and can cause corrosion.

I don't have a magic solution, but try to run my car throughout the year and put fresh gasoline in it. I know that is not possible for some people.

[Steve in Denver]

In Denver, there are Murphy's gas stations, they carry an Unleaded Ethanol Free gas, 87 octane. It is the one with the Blue handle.

[Tim Ayers]

Originally Posted by updraught

Because it is making Americans less and less intelligent it says.

LOL! Consider me a dumb ass because I'll mix a little 100LL into my non-ethanol gas. Granted, I'm running a highly hopped up flathead V8 in my '28 roadster, but the engine does like that mixture of 9:1.

[Herb Concord Ca]

I've given up on the tank or firewall valves. Both my cars have ball valves in the line up close by the sediment bowl. Have not had a problem in15 years.

[ModelA29]

100LL = 100 octane Low Lead aviation fuel. It's good fuel and has a longer shelf life. Do not use it in a car with a catalytic converter. The lower vapor pressure is so it's easier to start. My plane was certified to run car gas. The only change was a brass float instead of a plastic one in the carb. Here in CA it's our only option to get ethanol free fuel. It's only "illegal" to run on the highway because you didn't pay a road tax to use it on the street - kinda like an electric car......

Lead in gas acted as a lubricant for the valves and seats. New cars have hardened seats to reduce wear. Model As do not have enough valve spring seat pressure to have a wear problem. The low spring pressure also means you don't need zinc in the oil to protect the cam and lifters.

I always add Stabil to my Model A. A tank of gas can last me up to 3-4 months depending on weather so better safe than sorry with today's garbage fuel.

[Gene F]

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Originally Posted by Steve in Denver

In Denver, there are Murphy's gas stations, they carry an Unleaded Ethanol Free gas, 87 octane. It is the one with the Blue handle.

I wonder how that grade compares in price.