How old is too old for fuel?

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libertas

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libertas
Plane has been unused for 2.5 years and still has quite a bit of fuel in the tanks. I don't want to drain and dispose of that much fuel, but I don't want to do any damage to the engines. FWIW, I'm in a dry climate (CO), and it was always stored in a heated hangar. I did sump both sides, it was clean and smelled ok.

Also, if it does need drained, is there a simple, high volume way to drain it all from the sumps?
 
When my airplane under went a lengthy extensive overhaul, it sat for over 2 years. I (and the IA) pulled the quickdrain valves to drain both tanks. I donated the fuel to whoever wanted it. I think most of it went to the tugs used by the aeroclub.

I simply felt it was cheap insurance to not use it
 
libertas said:
Plane has been unused for 2.5 years and still has quite a bit of fuel in the tanks. I don't want to drain and dispose of that much fuel, but I don't want to do any damage to the engines. FWIW, I'm in a dry climate (CO), and it was always stored in a heated hangar. I did sump both sides, it was clean and smelled ok.

Also, if it does need drained, is there a simple, high volume way to drain it all from the sumps?
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Drain it and use it up in anything carbureted- your lawnmower, old snowmobile, golf cart, outboard, chain saw… they appreciate no ethanol and tolerate the lead.

I believe it’s technically ok, I think avgas preservatives are supposed to be good for 7 years- but I’d agree it’s cheap insurance to start fresh.

I bought a 150 this year on a aggressive buy-as is. she didn’t run as well as I’d like- and she didn’t make full static. I drained fuel n started fresh and she was a new woman! Believe it was mogas tho that has a shorter life, that plane had sat for 6 months. She ended up needing new mags too but the gas helped a ton too.
 
A bud dismantled the Ashland Terminal. 10+ years later they were working on the site and found a couple hundred gallons of 100LL. They used their testing capability and found it was as good as new.
I’ve also flown aircraft with 5 year old fuel. I’m no expert but my guess is the RVP (Reid Vapor Pressure ) would drop off due to the lighter ends evaporating if there was an issue.

Another guy had his aircraft down for Annual for about a year. Run up on av-gas was normal but switching to the mo-gas tank and the engine wouldn’t continue running.

Knowing type aircraft would be helpful.
 
kgruber said:
Use it in your 67'Corvette
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I like this idea^^^^^^^^ If only I had a 67 vette!
Like said above, remove the sump drain valves and loosen the fill cap. It will drain out smoothly and pretty fast. I not sure if you should do it in your hangar, outside would be best. Look for ignition sources before you start.

IMO it probably is still good but I would error on the side of caution especially after all the work that was done to your plane.

OT a little. We sell sunoco race fuels at work.
I stored a muscle car for 18 years with a full tank of sunoco 110 leaded race gas in it. I started the car about twice a year. I replaced the battery as needed and replaced gas as needed to keep the tank close to 100% full. 18 years later I started driving the car again, put close to 25K miles on it with the original gas tank and carburetor. Race gas has stabilizers in it right from sunoco and I have never added anything to it. Avgas is similar.

Also have used straight 110 leaded race gas in everything from small 2 and 4 strokes engines over the years. The small engines seemed to love the lead. They all ran well and lasted.
Bonneville after storage. Car is idling with the AC on a 90+* day.
Californiatrip7-1-10853.jpg

Californiatrip7-1-10854.jpg
 
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Magman said:
A bud dismantled the Ashland Terminal. 10+ years later they were working on the site and found a couple hundred gallons of 100LL. They used their testing capability and found it was as good as new.
I’ve also flown aircraft with 5 year old fuel. I’m no expert but my guess is the RVP (Reid Vapor Pressure ) would drop off due to the lighter ends evaporating if there was an issue.

Another guy had his aircraft down for Annual for about a year. Run up on av-gas was normal but switching to the mo-gas tank and the engine wouldn’t continue running.

Knowing type aircraft would be helpful.
Click to expand...
414A (TSIO 520).
 
Here is a about the best answer you will get.


The short answer is that, under most conditions, the shelf life of avgas is about one year. If you are a commercial operator, this is the end of the discussion.

For a private pilot, however, there are several points to consider. First, there is a large margin of safety in the one-year storage life of avgas. The main concern when storing fuels is oxidation and subsequent formation of gum. Once the fuel starts to form gum, it can cause problems in the entire fuel system. I’ve checked numerous avgas samples after two years or even more and found no degradation, with the samples meeting all specification requirements. The samples will last even longer if the container is blanketed with nitrogen or stored in a colder climate.
 
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