Got a Gas Problem ?
Thread Starter
Joined: Jan 2003
Posts: 517
Likes: 37
From: Kelowna Wine Country
Got a Gas Problem ?
Yes, I know, slight distortion to get your attention,
What is it about modern gas anyway, it is certainly not what it used to be. When I were but a sprogget I bought a Singer Nine in Oxford, it has been in a garage for two years, the gauge said I had half a tank of petrol, With a new battery it started right up and I drove it home to N Notts, no problem.
My last flight last year back in November was just a hop so I did not put in the two (plastic) cans worth of gas I was hauling around in the back of the car. (Rotax 912S on Mogas,) Seeing as how our local Muni is pretty well controlled by the greens now no one can build a gas station this end of town so we all have to drive 15K to buy the stuff and seeing how it was over the new year and the temp was down to minus 15C we let the gauge in our old guzzler get down to nil, well no problem, just dump in one of the cans. The poor old thing started playing up, well it might ,being that cold, might it not? Poor starting, missing while cold, bad bout of kennel cough, snorting like a unicorn, poor pick up, stalling at the lights (it's auto) couldn't be that surprised though, it has only had two oil changes and one plug change in ten years.
Next day wife 's new guzzler was also short so I dumped in the other can. Same result only with flashing lights, illuminated pictures of engines in distress, signs saying "take this car to your nearest dealer for ultra expensive service, do not pass go................"
So we wheeled them both down to the end of the town and filled them up with new gas, Instant cure.
Now you would think that if there was one engine that could suffer bad gas it would be your good old gas guzzling N American giant V8, so what, I am wondering, would be the effect of this stuff on my little Rotax come a couple of thousand feet? Be sure the first thing I am going to do when I get up to the airfield is drain the gas from my plane and replace with new.
So why does modern gas not last two months in a can?
And if you stash your plane three months over the winter BEWARE.
What is it about modern gas anyway, it is certainly not what it used to be. When I were but a sprogget I bought a Singer Nine in Oxford, it has been in a garage for two years, the gauge said I had half a tank of petrol, With a new battery it started right up and I drove it home to N Notts, no problem.
My last flight last year back in November was just a hop so I did not put in the two (plastic) cans worth of gas I was hauling around in the back of the car. (Rotax 912S on Mogas,) Seeing as how our local Muni is pretty well controlled by the greens now no one can build a gas station this end of town so we all have to drive 15K to buy the stuff and seeing how it was over the new year and the temp was down to minus 15C we let the gauge in our old guzzler get down to nil, well no problem, just dump in one of the cans. The poor old thing started playing up, well it might ,being that cold, might it not? Poor starting, missing while cold, bad bout of kennel cough, snorting like a unicorn, poor pick up, stalling at the lights (it's auto) couldn't be that surprised though, it has only had two oil changes and one plug change in ten years.
Next day wife 's new guzzler was also short so I dumped in the other can. Same result only with flashing lights, illuminated pictures of engines in distress, signs saying "take this car to your nearest dealer for ultra expensive service, do not pass go................"
So we wheeled them both down to the end of the town and filled them up with new gas, Instant cure.
Now you would think that if there was one engine that could suffer bad gas it would be your good old gas guzzling N American giant V8, so what, I am wondering, would be the effect of this stuff on my little Rotax come a couple of thousand feet? Be sure the first thing I am going to do when I get up to the airfield is drain the gas from my plane and replace with new.
So why does modern gas not last two months in a can?
And if you stash your plane three months over the winter BEWARE.
Why do it if it's not fun?
Joined: Jul 2001
Posts: 4,782
Likes: 12
From: Bournemouth
Fuel should last a lot longer than that. It doesn't have a very long shelf life, true, but a couple of months shouldn't be a problem.
Every time I've ever got a bad tank, it's been shortly after the petrol station has had a delivery. (Either I've seen the tanker leaving as I was pulling in, or else they've been closed while they were taking the delivery, and, since they were the only petrol station around, I've waited until the delivery was finished.) I think that, as the tanker pumps in hundreds of gallons of fuel at a pretty fast rate, it churns up the fuel that's in the tank, and all the crap which normally sits at the bottom of the tank gets mixed in with the fuel. Since I figured this out, I've always tried to avoid petrol stations which have just had a delivery, and I've never since had a bad tank. Could this be the cause in your case, I wonder?
I know that AvGas is regulated much closer than MoGas. I don't know if there are any rules in place to prevent this (e.g. cleaning out the storage tanks at AvGas retailers on regular basis) but I wouldn't be surprised if there were.
FFF
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Every time I've ever got a bad tank, it's been shortly after the petrol station has had a delivery. (Either I've seen the tanker leaving as I was pulling in, or else they've been closed while they were taking the delivery, and, since they were the only petrol station around, I've waited until the delivery was finished.) I think that, as the tanker pumps in hundreds of gallons of fuel at a pretty fast rate, it churns up the fuel that's in the tank, and all the crap which normally sits at the bottom of the tank gets mixed in with the fuel. Since I figured this out, I've always tried to avoid petrol stations which have just had a delivery, and I've never since had a bad tank. Could this be the cause in your case, I wonder?
I know that AvGas is regulated much closer than MoGas. I don't know if there are any rules in place to prevent this (e.g. cleaning out the storage tanks at AvGas retailers on regular basis) but I wouldn't be surprised if there were.
FFF
----------------
Joined: Apr 2003
Posts: 581
Likes: 0
From: Bordeaux, France
Avgas Delivery....
I know that at my Aeroclub here in France we do not allow the use of our fuelpump within the first three hours after a delivery of Avgas as a very minimum. And only in the 12 hours after delivery if absolutely necessary, and whoever wants it is told about the delivery and asked if they really need fuel today due to the mixing effect that FFF states above.
In fact I believe that the 3 hour wait may be a rule in France.
Regards, SD..
I know that at my Aeroclub here in France we do not allow the use of our fuelpump within the first three hours after a delivery of Avgas as a very minimum. And only in the 12 hours after delivery if absolutely necessary, and whoever wants it is told about the delivery and asked if they really need fuel today due to the mixing effect that FFF states above.
In fact I believe that the 3 hour wait may be a rule in France.
Regards, SD..
Joined: Feb 2001
Aviation Qualifications: PPL
Posts: 1,222
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From: Worcestershire, UK
Many people seem to be of the view that gasoline deteriorates with time due to evaporation of volatile components. This is not strictly correct.
These lighter components such as butane (and not ethanol as an earlier poster suggested) generate less heat in combustion than the heavier gasoline fractions. Therefore, after this evaporation, the fuel will actually have a higher octane rating than before.
In theory that makes it a better fuel. However the engine timing would have been based upon gasoline of the original octane rating, and hence missfiring can result. Not much consolation if your donkey stops over the Channel to know you've got "better" fuel
These lighter components such as butane (and not ethanol as an earlier poster suggested) generate less heat in combustion than the heavier gasoline fractions. Therefore, after this evaporation, the fuel will actually have a higher octane rating than before.
In theory that makes it a better fuel. However the engine timing would have been based upon gasoline of the original octane rating, and hence missfiring can result. Not much consolation if your donkey stops over the Channel to know you've got "better" fuel
Joined: Sep 2003
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From: UK,Twighlight Zone
ethanol alchohol is one of the additives put into Mogas for a number of reasons. It is not permitted for it to be put into Avgas. There is an article from the CAA that compares Avagas and Mogas and identifies the differences in the Mogas "cocktail" which forms part of the reason for the restrictions in the use of Mogas and the reason it is not allowed for Public Transport use.
I will find the .pdf link and post it.
I will find the .pdf link and post it.
Joined: Jul 2003
Posts: 139
Likes: 0
From: Minnesota
Refiners alter the composition of fuel (petrol) to suit the time of year. More lighter elements to aid in atomization during the winter, less lighter elements during the summer to prevent vapour lock in the fuel lines. I can't for the life of remember the formulae right now, but it seems you attempted to use summer formulated fuel in too cold a temperature. The whole thing is based upon the 'Reed Vapour Pressure Test'. I'm sure a short search in Google will provide you a good link.
Regards,
W.B.
Regards,
W.B.
Joined: Oct 1999
Posts: 3,325
Likes: 2
From: UK
Lawn mower repairers do good business every spring cleaning fuel systems of old mogas. If it's really bad, the carb can be scrap due varnish deposits.
We bikers who lay up our bikes over the winter have the same problem. Fuel stabiliser additive seems to be the answer.
SSD
We bikers who lay up our bikes over the winter have the same problem. Fuel stabiliser additive seems to be the answer.
SSD
Thread Starter
Joined: Jan 2003
Posts: 517
Likes: 37
From: Kelowna Wine Country
Posted the post on another forum too 'cos a good few of us lay up our Seareys for a couple of months over the Winter.
Seems this is now a common problem.
No, this was Winter Gas.
No, it was not bought just after a delivery, in fact it came from a virtually new gas station ( less than six months old) which has the latest envirosafe tanks and all the goodies.
No, it has no ethanol. Various formulations are supplied by the different manufacturers over here. I checked out the ethanol content of the various petrols as Rotax recommend low or no ethanol gas (something to do with seal life,) and Shell do not put it in.
(Just as an aside, in UK we had to close our station when receiveing petrol but here you can fill up while they are unloading into the tanks.)
Several replies on the other forum confirmed that this is a concern because modern petrols have additives apparently recognised as a common cause of various unhappy consequences. Also seems gas in plastic containers (which we did not have when I was sprogget) deteriorates faster that in metal.
Over here thay sell 'stabiliser' to be added when you expect gas to be stored for more than a month or so. Two months seems to be the accepted point at which problems start.
Of course you can be cavalier about this, that really is not the point nor the reason for post. I have been using cars and therefore gas for forty years and never before seen it as a problem. I could have has a nasty event for my ignorance. If you use mogas in your plane do not fly it on old stored gas, drain it into your car and let it fart its way home like mine. Put some nice new gas in your plane and fly safe.
Seems this is now a common problem.
No, this was Winter Gas.
No, it was not bought just after a delivery, in fact it came from a virtually new gas station ( less than six months old) which has the latest envirosafe tanks and all the goodies.
No, it has no ethanol. Various formulations are supplied by the different manufacturers over here. I checked out the ethanol content of the various petrols as Rotax recommend low or no ethanol gas (something to do with seal life,) and Shell do not put it in.
(Just as an aside, in UK we had to close our station when receiveing petrol but here you can fill up while they are unloading into the tanks.)
Several replies on the other forum confirmed that this is a concern because modern petrols have additives apparently recognised as a common cause of various unhappy consequences. Also seems gas in plastic containers (which we did not have when I was sprogget) deteriorates faster that in metal.
Over here thay sell 'stabiliser' to be added when you expect gas to be stored for more than a month or so. Two months seems to be the accepted point at which problems start.
Of course you can be cavalier about this, that really is not the point nor the reason for post. I have been using cars and therefore gas for forty years and never before seen it as a problem. I could have has a nasty event for my ignorance. If you use mogas in your plane do not fly it on old stored gas, drain it into your car and let it fart its way home like mine. Put some nice new gas in your plane and fly safe.
Joined: Feb 2001
Aviation Qualifications: PPL
Posts: 1,222
Likes: 2
From: Worcestershire, UK
Sorry guys, but a lot of what has been written is not strictly correct. I work as an expert consultant to the oil industry, and am a member of the Institute of Petroleum, so I do know what I'm talking about.
The Reid Vapour Pressure (RVP) specification for gasoline referred to above is indeed adjusted seasonally to prevent possible vapour lock. In summer, when the fuel will be warmer, it is necessary to have a fuel with a lower RVP. In winter, it can be higher without causing a problem. Therefore, there is no problem using a summer grade in winter, but on a particularly hot day, there can be a chance of vapour lock with a winter grade fuel. This is dependant on a fuel delivery system, and the requirement to retain a NPSH (net positive suction head) The calculation of NPSH is a rather complex business, and it is dependant on the RVP amongst other things.
The vapour pressure is a function of the volatile components. Butane is the main volatile component in a modern gasoline, which for commercial reasons nowadays will almost certainly be a product known as RFG (reformulated gasoline). Ethanol is not particularly volatile, and hence has a low RVP. In Europe, Ethanol trades at about $500 per ton, and Butane about $250 ton. Simple economics dictates which product gasoline blenders use! European gasoline specs also specify a maximum of 14% alcohols in the blend (Ethanol is ethyl alcohol)
However Ethanol (and more usually methanol - Methyl alcohol) is used in gasoline in greater quantities in refining countries with plentiful access to ethanol and limited access to butane. This is generally 3rd world countries, where ethanol is typically produced from the fermentation of sugar beet.
However these materials will not meet European or US Gasoline specs.
With regards to ChrisVJ's point about gas deteriorating faster in plastic, it's true that butane molecules can more easily pass through plastic than tin. For that reason, plastic sample bottles are not generally used for volatile materials such as Gasoline. My job often involves analysis of samples weeks, months (or even years) after shipment, and gasoline samples stored in plastic bottles are useless for this purpose.
Chris is also correct that ethanol can adversly effect synthetic and natural rubber seals. I definately agree with his final comment - "put some nice gas in your plane and fly safe". Sound advice.
The Reid Vapour Pressure (RVP) specification for gasoline referred to above is indeed adjusted seasonally to prevent possible vapour lock. In summer, when the fuel will be warmer, it is necessary to have a fuel with a lower RVP. In winter, it can be higher without causing a problem. Therefore, there is no problem using a summer grade in winter, but on a particularly hot day, there can be a chance of vapour lock with a winter grade fuel. This is dependant on a fuel delivery system, and the requirement to retain a NPSH (net positive suction head) The calculation of NPSH is a rather complex business, and it is dependant on the RVP amongst other things.
The vapour pressure is a function of the volatile components. Butane is the main volatile component in a modern gasoline, which for commercial reasons nowadays will almost certainly be a product known as RFG (reformulated gasoline). Ethanol is not particularly volatile, and hence has a low RVP. In Europe, Ethanol trades at about $500 per ton, and Butane about $250 ton. Simple economics dictates which product gasoline blenders use! European gasoline specs also specify a maximum of 14% alcohols in the blend (Ethanol is ethyl alcohol)
However Ethanol (and more usually methanol - Methyl alcohol) is used in gasoline in greater quantities in refining countries with plentiful access to ethanol and limited access to butane. This is generally 3rd world countries, where ethanol is typically produced from the fermentation of sugar beet.
However these materials will not meet European or US Gasoline specs.
With regards to ChrisVJ's point about gas deteriorating faster in plastic, it's true that butane molecules can more easily pass through plastic than tin. For that reason, plastic sample bottles are not generally used for volatile materials such as Gasoline. My job often involves analysis of samples weeks, months (or even years) after shipment, and gasoline samples stored in plastic bottles are useless for this purpose.
Chris is also correct that ethanol can adversly effect synthetic and natural rubber seals. I definately agree with his final comment - "put some nice gas in your plane and fly safe". Sound advice.
Joined: Oct 1999
Posts: 3,325
Likes: 2
From: UK
Mariner9
Thanks for that. Can you give a definative 'life' for unleaded motor fuel in UK? If I cease to use my motorcycle for 4 months of the year do I really need to put fuel stabiliser in the tank? (Honda Blackbird with metal tank and carburettors, not FI).
If I do put stabiliser in, and run the engine so it fills the carb bowls with 'stabilised' fuel, will that provide full protection for 4 months? Or am I wasting my money putting in the staibiliser?
Hope you can help. There seem to be differing views on all this.
SSD
Thanks for that. Can you give a definative 'life' for unleaded motor fuel in UK? If I cease to use my motorcycle for 4 months of the year do I really need to put fuel stabiliser in the tank? (Honda Blackbird with metal tank and carburettors, not FI).
If I do put stabiliser in, and run the engine so it fills the carb bowls with 'stabilised' fuel, will that provide full protection for 4 months? Or am I wasting my money putting in the staibiliser?
Hope you can help. There seem to be differing views on all this.
SSD
Joined: Feb 2001
Aviation Qualifications: PPL
Posts: 1,222
Likes: 2
From: Worcestershire, UK
Nice bike SSD!
Unfortunately I cant give a definitive shelf life; it's dependant on loads of factors such as fuel manufacturing process, storage conditions, temperature and humidity variations, etc etc.
Fuel stabilisers are generally oxygen stability improvers. These surpresses the formation of corrosive peroxides arising from exposure to oxygen. Unfortunately they have no effect on the loss of volatile components through evaporation. A simple (and cheaper) alternative to stabilisers is to keep your tank full; this would reduce the surface area to fuel volume ratio. This also helps with the loss of volatiles, and would reduce the quantity of water condensing from the air above the fuel within the tank.
Another factor on shelf life for leaded fuels such as 100LL or 4 star would be the loss of lead content. The lead, which is added to gasoline in the form of tetra-ethyl lead, will coat any metallic surface over time, and in prolonged storage the concentration remaining in the fuel may fall below engine-specified limits. This could ****** your valves and cylinders, and really ruin your day.
Unfortunately I cant give a definitive shelf life; it's dependant on loads of factors such as fuel manufacturing process, storage conditions, temperature and humidity variations, etc etc.
Fuel stabilisers are generally oxygen stability improvers. These surpresses the formation of corrosive peroxides arising from exposure to oxygen. Unfortunately they have no effect on the loss of volatile components through evaporation. A simple (and cheaper) alternative to stabilisers is to keep your tank full; this would reduce the surface area to fuel volume ratio. This also helps with the loss of volatiles, and would reduce the quantity of water condensing from the air above the fuel within the tank.
Another factor on shelf life for leaded fuels such as 100LL or 4 star would be the loss of lead content. The lead, which is added to gasoline in the form of tetra-ethyl lead, will coat any metallic surface over time, and in prolonged storage the concentration remaining in the fuel may fall below engine-specified limits. This could ****** your valves and cylinders, and really ruin your day.
