Posted: 8/5/2009 9:19:15 AM EDT
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There have been a lot of questions posted on the time period for storage of gasoline and I wanted to throw some information into the ring to help you make a decision on what you are buying…
I am not involved in the fuel industry or a chemist. My job requires that I be knowledgeable about fuels for use in the equipment we are involved in. I am required to attend classes regarding fuels and some basic testing procedures for fuel quality. You can take this or leave this… It isn’t cut and dry to answer “How long will the fuel last…”. There are too many variables. The greatest being the quality of the fuel you have purchased from the get go. Stick with major brands here. You will be paying more for the fuel but the quality and freshness from the start will be better. Buy from a brand that has their fuel “Top Tier Rated” http://www.toptiergas.com/. The better the cleaners and detergents (and amount) will help keep the engine clean inside, where it matters. If you want a detergent/cleaner to add on your own, we have found Pro-guard ™ (Techron) to be one of the best. Application This also plays a role. Is this for your car? Genset? Outdoor power equipment? Each one has their own unique operating conditions. Old fuel that runs good in your car may be instant death for your large displacement chainsaw. All air cooled engines are going to be more stressful on the quality of the gasoline that is run in it. In a four stroke-cycle engine the fuel takes a more direct path from the carb/fuel injector through the intake, past the valve, directly into the combustion chamber. In a two stroke-cycle engine, the fuel first enters the intake tract, crankcase (where it is pressurized), and then travels up the transfer ports into the combustion chamber. There is more area to pick up heat from in the two stroke. Poor fuel can instantly stick a ring in a two stroke or glue it together after it cools down. Fuel makeup Typical base gasoline is made up of light virgin Naphtha, Catalyst cracked gasoline, Butane, Alkylate, and Reformate. Additives include antiknock, antioxidant, corrosion inhibitors, metal deactivators, detergents, demulsifiers, dyes, and oxygenates (ethanol or MTBE). Other additives may be blended in for your area, for example, anti-icing additives for North Dakota would not be needed in Florida. Once blended these fuels are classified by their octane rating for the average user. Use the fuel that has the octane rating your engine manufacture requires for proper power output and engine life. Some of these additives are blended to the fuel when the fuel is going into the tanker truck for delivery to the appropriate stations. Yes, you may find Mobil, Texaco or Wally World trucks loading at the same depot. They may be getting the same base fuel, but it is the proprietary detergent additive package that makes them unique which is added at this time. It costs more to put the good stuff in. Cheaper fuel is cheaper for a reason. That less expensive fuel at the no name pump may be old fuel that already is varnishing and gummed up. Octane Most people incorrectly think the higher the octane fuel the more power they will get from their engine. This is only true if the engine is designed to run on that higher octane fuel. Using 87 octane fuel in an engine that is designed to run on 91+ octane will result in a loss of power if the engine is computer controlled, and possible detonation (explosion of the fuel) or pre-ignition (burning before the spark) damage to that engine, especially if it is not computer controlled. The octane rating does not correlate to how fast/slow the fuel burns or how hot/cold the fuel burns. Gasoline on an average burns at around 115,000 BTU. If the speed of the burn was different you would need to change your ignition timing every time you filled up with a different fuel. Octane is simply the fuels ability to resist knock (detonation). Most of us remember that lead was added to fuel to increase the octane and as a lubricant. We need a controlled even burn of the fuel in the combustion chamber to extract the maximum amount of power from it. An explosion is not a controlled burn. Think of it this way… if lay out a foot long stream of your favorite gunpowder on the ground and light one end. See how long it takes to burn. It takes quite a long time. However, pack that same amount in a small container with no excess space, poke a small hole in the container and add a fuse. Light it and ka-boom, gone instantly. Pressure increases dramatically. That is what we are trying to avoid in that engine. That is what happens when your engine “knocks” or “pings” during acceleration or under heavy loads. The fuel is exploding. Use the fuel your engine mfg requires. http://faqs.cs.uu.nl/na-dir/autos/gasoline-faq/part3.html. If we take away the fuel, our engine is simply nothing but an air compressor (air pump) if we turn the crankshaft. Just the process of compression creates a lot of heat. If you own an air compressor, let it run and build up full pressure and check the temperature of the outlet pipe from the compressor head. You will be surprised. The fuel inside the combustion chamber of an engine must resist this heat and not be ignited or break down from it. Fuel deterioration As fuel ages it oxidizes and becomes “stale”. It turns amber color and smells like varnish. Gums are formed which are not clean burning. They lower the octane of the fuel and when burned leave deposits and tar behind on engine components. This acts as an insulator and heat cannot be dissipated as needed. Area has now diminished so oil film is not as thick as should be causing friction and more heat. This is deadly to an air cooled engine. For long term storage it would be better to buy the higher octane fuel since in theory it should take longer to reach a low enough octane rating to be insufficient. Ethanol (pure grain alcohol) Here is where things get interesting, and I could write a whole separate post on this one. The EPA required oxygenated fuel in the 1990 Clean Air Act to reduce pollution from engines that were not computer controlled. This simply mixed the oxygenate (ethanol) with the gasoline, causing the mixture to be leaner (more oxygen/less fuel) in the combustion chamber. This also has the effect of increasing engine temperature. Many states now have been requiring the use of Ethanol to meet Renewable fuel standards. I see where guys post “I have had fuel stored for 2 years and my wife’s Honda civic runs great on it”. Most likely that fuel does not contain ethanol. Areas such as Florida, PA, MN and MA are seeing ethanol for the first time, or its use has been expanded. Florida just started seeing ethanol blends since late 2007 early 2008 for the first time. Try doing that now and you will not be so lucky. Two bad things about ethanol (other than a hang over!), it is an oxygenate and it loves water. Remember, oxygen is what makes fuel deteriorate and go stale. That is why antioxidant additives are put into the fuel. These are to keep the fuel from deteriorating too quickly, but they are consumed in that process, so its protection will be less as the fuel ages. The greater the amount of antioxidants, the longer that fuel will last. Just remember, any ethanol in the fuel is working against the antioxidants. Try and find fuel in your area that does not contain ethanol for long term storage and add antioxidants to it yourself. You can try local marinas; some are carrying fuel without ethanol due to its effects on fiberglass fuel tanks in boats, and its affinity for water and corrosion. Remember, ethanol loves water. ½ of 1% of water by volume can cause the ethanol to phase separate out to the bottom of your fuel tank (water is heavier than gasoline). This is bad for engines that require fuel/oil mix since the fuel pickups are at the bottom of the tank, but there is no lubrication. This will cause almost instant seizure of a two stroke-cycle engine due to the alcohol washing off the lubrication inside that engine. As a side note, from the point that ethanol was added to the fuel the whole fuel distribution line is now being cleaned (ethanol is also a good cleaner) and water is being picked up because of the ethanol. If ethanol is just being brought into your area, expect dirt/varnish/water problems for the next year or so until you clean everyone’s fuel delivery system for them. Lastly, don’t be trying to phase separate the ethanol from your local fuel to do shots, it has been denatured so you can’t drink it. Consider purchasing a gasohol tester from a Briggs and Stratton or ECHO dealer to test your fuel. Additional Additives Well how do you make fuel last for a long time? What can I add to make it last longer? If you are mixing for a two stroke-cycle engine mix only fresh fuel in an amount that you can use in a 1-2 month time frame. Any longer then that and you are asking for trouble. The oil mix may contain a stabilizer product, but you are adding oil (and other additives) which could lower the octane and life of the oil. Mix up only what you can use in a short time frame. Use the oil your engine mfg requires. As for additives, I have found that Pro-Guard ™ (Techron) is a great fuel system cleaner to add. This is Chevron’s proprietary detergent for their fuel. Stabil is an antioxidant to add to fuel. They have a “marine” version that has more antioxidant and corrosion inhibitors in it. While I have not personally tested it, this would be the way to go for long term storage. Conclusion For storage, buy the higher octane fuel that is ethanol free, you will have a longer time before it deteriorates to too low of an octane. Add your own antioxidant/stabilizer to your fuel. Keep as much oxygen (sealed containers, preferably non permeable – HDPE is permeable to gasoline) away from the fuel as possible. Keep the fuel as cool as possible as heat will also accelerate its deterioration. Keep in mind your mileage (no pun intended) will vary due to the various conditions present on fuel storage. |
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Quoted:
I just use PRG and be done with it, last for years. The thing I've head is worst is storing it where it does not have a stable temperature. Ideally you want to put it somewhere that it stays relatively cool all the time, and with as little daily temperature swings as possible. My problem is safely storing 50 gallons of fuel.
For most people the only place they have that's usually cool is the basement, but obviously that's less-than-ideal. The other stable-cool-temperature place that survivalists tend to have is their underground shelter––but obviously they don't want it all in there either. –––––– I don't "know" much techincal, just have heard people try to store fuel and the problems they've had. The other thing I've heard of gasoline stores causing problems is that if it has sat for more than a few months, you really need to stir it up again before using it. It will tend to stratify quite a lot; in particular the heavier harder-to-burn stuff all sinks to the bottom. For a gas can you can just shake it up. For a stationary tank or a 55-gal drum, they make "paint" mixers that are long enough to reach the bottom of a 55-gal drum, but the problem is that electric drills create sparks as they spin, so you need to use a hand-crank drill. ~ |
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Quoted:
Excellent thread! It would be nice if the OP would double post this thread in the Survial Forum where it would get even more positive views. (Hint, Hint) Posted it there 060109, it got 2 posts  Now it's in the Archive. It was suggested by ScrubJ to bring it to GD.
ETA: http://www.ar15.com/archive/topic.html?b=10&f=17&t=624335 |
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Quoted:
Quoted:
I just use PRG and be done with it, last for years. The thing I've head is worst is storing it where it does not have a stable temperature. Ideally you want to put it somewhere that it stays relatively cool all the time, and with as little daily temperature swings as possible. My problem is safely storing 50 gallons of fuel.
For most people the only place they have that's usually cool is the basement, but obviously that's less-than-ideal. The other stable-cool-temperature place that survivalists tend to have is their underground shelter––but obviously they don't want it all in there either. –––––– I don't "know" much techincal, just have heard people try to store fuel and the problems they've had. The other thing I've heard of gasoline stores causing problems is that if it has sat for more than a few months, you really need to stir it up again before using it. It will tend to stratify quite a lot; in particular the heavier harder-to-burn stuff all sinks to the bottom. For a gas can you can just shake it up. For a stationary tank or a 55-gal drum, they make "paint" mixers that are long enough to reach the bottom of a 55-gal drum, but the problem is that electric drills create sparks as they spin, so you need to use a hand-crank drill. ~ Cool stable temperature the better. Sorta on the mixing. Remember, gasoline is lighter than water and other solids. if there is separation You DON'T want to mix it back in to the gasoline that is on top of it. Remove it! One thing to remember is that if the fuel had ethanol in it, and that ethanol has separated with water to the bottom of your tank, the fuel left above has a lower octane since it does not contain the ethanol which is also an octane booster. So if you started with 89 octane fuel with 10% ethanol and it separated, and you remove the ethanol/water from the bottom, the fuel left is about 87 octane. |