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Old Fuel

10 year old fuel

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Frank Skilbeck29/07/2019 07:59:57
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I have been given a couple of gallons of Southern Modelcraft 0% nitro synthetic fuel which is approx 10 years old, while it is in unopened sealed containers it appears slightly darker than the fuel I bought last year. Is it worth giving it a try?

CARPERFECT29/07/2019 08:20:11
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504 forum posts
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Good for weed killer

Jon - Laser Engines29/07/2019 08:33:33
5418 forum posts
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The oil tends to go brown after a while as the purple dye degrades. I would give it a go and see what happens. If the engine runs like junk, its likely the fuel is no good.

Paul Marsh29/07/2019 08:52:00
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its probably ok, if the engine runs poorly on the ground - usually when you take the glo clip off, the engine runs poorly or stops, is a good indication on bad fuel.

Full containers with little air would be better than half used bottles, where the fuel has absorbed water and would be useless.

Try it out on an trainer plane/engine to check, if ok, use it up.

Don Fry29/07/2019 08:57:06
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4557 forum posts
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If it's sealed, I would be surprised if it's not fine. Some time back, I "found" some lost unopened containers in the cubbyhole I store wine. Cool but damp. 10 years old. It was fine.

David Davis29/07/2019 10:26:36
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3677 forum posts
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I agree with everybody else. In the past I've even slung a little petrol into the mix!

Peter Miller29/07/2019 10:34:14
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10947 forum posts
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I was asked to check out a buggy. I was given half a gallon of high nitro fuel which was seven years old.

It still worked perfectly

Doc Marten29/07/2019 10:48:34
542 forum posts
7 photos

This always interests me.

There is an article in one of the RCM&E online back issues where they visited the Model Technics factory and interviewed the brains within the company, he stated that model fuel is only mildly Hygroscopic, I can't remember the exact wording but after reading it I came away with the impression that water absorption over time isn't a concern.

Lima Hotel Foxtrot29/07/2019 11:11:11
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382 forum posts
Posted by CARPERFECT on 29/07/2019 08:20:11:

Good for weed killer

In fact, the best weedkiller I've found!

Jon - Laser Engines29/07/2019 11:24:08
5418 forum posts
263 photos

I think it depends on the circumstances Doc. a full gallon in a sealed bottle is going to last for ages. A 1/3 gallon in the bottom of a bottle that has been opened and closed a bunch of times is another story.

My enya 120 used to run fine when my fuel was new but when my gallon got down towards the bottom 1/3 the engine just woudnt run as smoothly. Change to a fresh gallon and it was back to its normal happy self.

To be fair that was the only engine i have ever seem exhibit that behaviour but it certainly seemed to show there was some change in the fuel as the gallon got used up. Most certainly the colour changed from bright purple to a more dirty purple colour.

The only other one that springs to mind was a customer who couldnt get his laser 100 to run right. I recommended all the usual stuff including asking him to use a new gallon of fuel and it was all without success. In the end he came to the factory with the engine and it ran perfectly on my fuel. I asked him if he had his gallon of fuel with him, which he did.... oh dear. It turned out both his original gallon and his 'new' gallon of fuel were taken from a stock of about a dozen he rescued several years previously from the shed of a modeller who had been dead about 5 years before that. It was irvine sport 5 (usually red) and it had turned a muddy brown colour. Goodness knows what was wrong with it, but it looked like after run and smelled really acidic. He was most aggrieved when i told him all of his fuel was useless and he would have to take it to the dump.

Bruce Collinson29/07/2019 11:53:47
511 forum posts

Jon's latter reflects my recent experience with both a Laser 100 and a Saito 125, neither of which was happy with relatively fresh - 18m max? - Laser 5, but part used and when referenced against newer identical fuel it was noticeably darkened.

It killed some weeds.

Personally, with a gallon at £20 versus the sort of in-the-air cost of anything using a 100/125 up front, I won't risk it any more. UV appears to be unhelpful. Hypothetically, with a Saito or ASP, exhaust pressure could deposit something in the tank which then gets emptied back into the fuel bottle ... not with a Laser, no exhaust pressurisation ...just a thought.

BTC

Martin Harris29/07/2019 13:16:27
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9262 forum posts
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That's been my speculative theory with my fuel (Southern Modelcraft) which does seem to change colour as it's used - probably combustion products being put back when emptying the tanks at the end of a session.

The amount of water held in the air in a half empty gallon bottle at average temperatures and humidity in this country is negligible - probably less than a single drop - so water absorption should not be a problem unless the bottle is left open to the air for extended periods.

My fuel is normally never older than a few weeks at any time of the year but I do have a stock of Model Technics Duraglo which I inherited along with a lovely old Stearman and instructions from the previous owner that this was the only fuel to be used with the RCV engine which was the latest of long line of power plants to power the model (before Westons became RCV suppliers and changed the recommendation this just happened to be the fuel sold by the previous distributor). I've largely abided by his wishes and the (probably) 10 year old fuel, despite (or in his opinion because of) its high castor content continues to work well.

Levanter29/07/2019 14:49:55
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882 forum posts
437 photos
Posted by Don Fry on 29/07/2019 08:57:06:

If it's sealed, I would be surprised if it's not fine. Some time back, I "found" some lost unopened containers in the cubbyhole I store wine. Cool but damp. 10 years old. It was fine.

And the wine tasted pretty good too ….. hic!

Jon - Laser Engines29/07/2019 15:00:01
5418 forum posts
263 photos

Martin i think you are right about the moisture thing to some degree but if you consider how most fuel is stored its far from ideal. We leave it in the sun all day, usually with the top off or a loose fitting cap of some sort. We then take it home and stick it in a cold garage or shed where any moisture that is in the air can condense out. Admittedly, this isnt a problem if the fuel gets used quickly but if it takes many months to get through a gallon i can see these various contaminants causing a problem.

That said, perhaps a great deal of this fuel going off business is out of date. When we all used 20-40 size 2 strokes our fuel consumption would be very much lower than now with 90 and 120 4 strokes being considered normal sizes. I definitely use fuel long before it has a chance to go off. I can do a gallon in a weekend if i fly my big warbirds extensively.

As for duraglo, you might as well run it on chip fat for all the good that stuff will do to it

Torsten Spitzner29/07/2019 15:14:00
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33 forum posts
21 photos
Posted by Lima Hotel Foxtrot on 29/07/2019 11:11:11:
Posted by CARPERFECT on 29/07/2019 08:20:11:

Good for weed killer

In fact, the best weedkiller I've found!

That's no lie. Bit expensive though, generally. And stains the paving.

Shaun Walsh29/07/2019 15:19:52
299 forum posts
49 photos

There's no fuel like an old fuel..................................

I'll get my coatblush

Jonathan W29/07/2019 15:25:41
120 forum posts
11 photos

One thing that WILL make fuel go off is using a brass clunk weight on the end of the pick-up pipe dangling down from the bottle top. My dad left a bottle of his like that for a couple of years. The fuel looked like Guinness and the brass looked like something from Roman remains.

I've got a stainless steel clunk in my bottle and it still looks like new after a number of years permanently living in 10% nitro.

Frank Skilbeck29/07/2019 16:37:13
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4681 forum posts
101 photos

They are full unused/unopened containers stored in a shed/garage, I'll give them a go and report back.

Martin Harris29/07/2019 18:05:53
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9262 forum posts
245 photos
Posted by Jon - Laser Engines on 29/07/2019 15:00:01:

Martin i think you are right about the moisture thing to some degree but if you consider how most fuel is stored its far from ideal. We leave it in the sun all day, usually with the top off or a loose fitting cap of some sort. We then take it home and stick it in a cold garage or shed where any moisture that is in the air can condense out.

I know a lot do but other than a small vent hole, the only time mine is open to the air is when I pop in the tube connector bung that I made back at the turn of the century when I start a fresh gallon.

Former Member29/07/2019 20:16:10
3577 forum posts

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