Sorry - Fuel Again.

[Robin_Holden]

Hello from Spofforth village in North Yorkshire,

Sorry to bring up fuel yet again , but I need your views on how long I can store fuel ?
I use fuel containing 80% methanol , 15% synthetic and 5% nitro.
It is always stored in a steel container.

How long before it deteriorates do you think ?
I’m asking because a couple of days ago my Brodak 40 , which has never missed a beat , suddenly started to misbehave.
And by the way, this fuel  is over 12 months old.

Any contributions much appreciated.

Robin

[Robin_Holden]

Sorry chaps , senior moment.
My fuel should have read :
75%  methanol , 15% synthetic , 5% castor and 5% nitro.
Sorry again.
Robin.

[Dan Berry]

Fuel lasts years if it is sealed tightly.
If it isn't sealed well alcohol and nitro evaporate and you then you have fuel with too much oil.
What you DON'T have is fuel with absorbed water.

[Dave_Trible]

I have used fuel over fifteen years old-   Actually I have a can of K&B 100 from around 1970 that ran OK on the test stand.  I recently gave that gallon away to a newbie to fly with.  As Dan said though you have to try not to let it absorb moisture of evaporate contents.   Another thing-don't set your containers directly on concrete for any period of time.  I can't really explain what happens to it but it will ruin the fuel over time.  If you need to store it on concrete just put down a piece of wood on the floor first.   I do think transferring fuel from plastic to metal cans is a good idea.   If nothing else it blocks light which may help preserve it and not too sure plastics don't leach chemicals into the fuel at some point.  I have plastic jugs with fuel where the fuel turns green if all castor or orange where the red oil has been used.

Dave

[Brett Buck]

Hello from Spofforth village in North Yorkshire,

Sorry to bring up fuel yet again , but I need your views on how long I can store fuel ?
I use fuel containing 80% methanol , 15% synthetic and 5% nitro.
It is always stored in a steel container.

How long before it deteriorates do you think ?
I’m asking because a couple of days ago my Brodak 40 , which has never missed a beat , suddenly started to misbehave.
And by the way, this fuel  is over 12 months old.

  I routinely use fuel 5+ years old, I think there should be effectively, no limit. That presumes it is stored in a metal can, properly sealed and not rusted, and didn't have any contaminants to begin with. A year should be nothing at all, I think I ran about 10-year-old fuel, previously opened in maybe 2015, at the NATs last year.

     If there was something that shouldn't have been there in the first place, some sort of contaminant, then all bets are off. Looks for flakes at the bottom of the can - white or bluish flakes are the nitro decomposing, because there is something else in there.

   I would suspect a lot of other things before fuel *age*, there's a lot of other things that can go wrong with an engine, or, there is something wrong with the fuel other than mere age. The test is, presumably, obvious - get new fresh fuel straight from an unopened can, try that.

     Brett

[Robin_Holden]

Very much obliged to all who contributed.
Robin.

[Steve Thompson]

Yesterday I was running 20-year-old Byron 10% fuel with a price on it of 14 bucks.

I wanted to know if it was still viable fuel and test subject was an expendable RC job with LA40.  Prior to flight, I shook fuel and examined in a clean pickle jar for any contamination or signs of separating castor stuff and found nothing.  I also did a flight with 3-month-old Brodak 10% fuel for comparison.  3 flights on old stuff and one on new.

No stalling at idle and max power was about the same, I think slightly less power with old stuff but very close.  Transition from idle to full power was a little better with new stuff but engine never quit/stalled with either fuel.  I assume some loss of nitro occurred.  Old fuel was 1/3 gallon that has been stored with a good sealing cap that is plumbed for silicon lines and crank fuel pump, which have been attached the whole time.

I do not recommend using old fuel.  This was done in the name of science, cuz I wanted to know.  My conclusion:  It worked yesterday.  My advice:
 Don't risk a plane you care about with old fuel.

[Dan McEntee]

   As already stated, a lot depends on how you store it. I have opened 40 year old cans of Cox fuel, and engines started on it first flip and ran fine. The cool , dry, constant environment out of direct sunlight helps tremendously. Sometimes the fuel you like and need can be difficult to obtain, so when the opportunity presents itself, buying in bulk and stocking up becomes necessary.  While the SIG C/L contest was going strong, I always picked up a couple of cases of fuel whether I needed it or not, since no one here where I lived stocked it. I always marked it up with when I bought it, kept it in the cardboard cases and stored in my basement. I have been through countless gallons of fuel that way. I don't recall ever having a problem doing this. I am still working on the last of the SIG fuel we made a special trip to Montezuma to pick up when they finally started mixing some again after the pandemic. I am mixing my own now when I need something I don't have in my stash in the basement. If I ever had any questionable fuel, I just mixed it n with a known good jug of fuel a little at a time and that worked out good for sport flying and fun flying. I'm just cheap and hate to waste anything. My stock got really low during the pandemic, and I eventually went through all the questionable fuel I had this way.
  Type at you later,
    Dan McEntee

[Peter in Fairfax, VA]

Yes, glow fuel from the 1970's is still good, if stored well.  For some reason, the test is often an old gallon of K&B.

In recent mixes I've been making up, I run a little bit of castor oil, like 3% or 5%, and like to shake the gallon jug before dispensing the liter I take to the field.

[dennyleo]

I had a partnership with 2 co-worker chemical engineers in the early ‘60s and we sold fuel through many hobby shops in Upper Midwestern states as well as in 55-gallon drums to R/C clubs.  I had great engine runs with some of that fuel 25 years later.  We used synthetic oils as well as a great supplement for the castor oil when we used it.

If your fuel has gone “bad”, castor oil is the likely culprit.  Yes, methanol is great at absorbing water, but castor oil will go rancid in many conditions -

https://castoroil-guide.com/can-castor-oil-go-bad/

Storage in sealed containers and in a dark, cool place is best.

Dennis