(Continued from Part 1. This concludes the article.)
Fuel Restoration Techniques
These suggestions are appropriate as means of ‘last resort’ in an attempt improve a degraded fuel. Another advantage of storing Avgas is that we can blend it with other gasolines to bring up the octane level and to dilute the degraded automotive gas. Dilution is the solution. The combination of non-ethanol unleaded premium and Avgas 101LL can restore the depleted octane level of the automotive gasoline (Mogas) that has lost its octane rating over a one-year or much longer period of time. This blend can bring it back closer to a level that our chainsaw manufacturer recommends as the minimum needed to operate the saw without damaging it. For modern Stihl brand chainsaws, this minimum octane rating is 91. Older generators that are 4-cycle engines are designed to be low compression motors that can operate well on degraded stored gasoline with a reduced octane level.
Very old automotive gas could be blended in small proportions with fresher gasolines, or Avgas to extend our fuel reserves. A word of caution: Do not mix too much of this old gasoline that smells like turpentine in with too little fresh gas, or attempt to use it even if runs the engine after the engine is started with a fresher fuel, as it might cause lacquer to build up on the compression rings and ruin the motor.
If we are desperately low on gasoline, yet there happens to be a few gallons of white gas (Coleman fuel) and we need to run a small generator to charge batteries or a chainsaw, we can blend in:
3 parts 96 octane Avgas (Aviation gasoline) with one part white gas,
or,
4 parts fresh automotive gasoline with with one part white gas.
Fresh Avgas has an octane rating of 96. White gas, 55. As a estimate only, we can ballpark the octane level of this blend of fuels by a simple calculation that roughly gauges the octane level of our fuel blend. Where 1 part Avgas is, then use the number 96. And for 1 part of white gas, use the number 55. To find the average and the resulting octane level of a blend: 96+96+96+55 divided by 4 = 85.75, the approximate octane rating.
And if there is 75% or higher in concentration alcohol available, we can further improve the octane level, by adding enough until the motor ceases to ping, or knock. Because 4-cycle small motors are generally lower compression motors, this blend might be satisfactory. If not, then add a bit more Avgas, fresh automotive gas, alcohol, or toluene.
Instead of white gas, if we only have degraded automotive gasoline to extend our dwindling supply, the same approach can be taken. Of course, the octane level of the old fuel would be unknown and we would have to just do the best we can, and mix in only one part for every three parts of Avgas, or less. If the motor pings or knocks, then we can add alcohol or toluene to further increase the octane level. In the event that we must run this blend in a motor “as is”, only run the motor for short periods and lower speeds, so that it does not become too hot, and create the conditions where there is risk of melting a hole in the piston.
Restoring Old Fuel
As a last resort, to restore old fuel that has gone flat, or improve a fuel blend using old fuel, that will not start or run an engine well, we can spray in lots of ether if we have it, or slowly bubble into the fuel, some propane or butane, to improve it. This can be done using a propane torch by slowly opening the valve, so that only a small number of small bubbles come up from the bottom. In a large fuel container, a hose can be attached and fed as far down into the reservoir as possible. Open the valve so that only a small amount of propane bubbles are produced and very few of these bubbles reach the surface. This allows most of the propane used to be absorbed by the gasoline and not wasted. Ideally, the fuel should be stirred to become exposed to the propane. Stirring the fuel could be done via excessive bubbling using propane, or better yet, by using an electric fuel pump to circulate and mix fuel while slowly bubbling in propane.
Propane will naturally and quickly be dissolved and dispersed in the fuel until the fuel becomes saturated. Once the slow rate of bubbling is no longer adding propane to the fuel, most of the bubbles can be seen to reach the surface. If there is only a small amount of old gasoline to be refreshed, one can simply spray ether directly into the fuel, and use ether to start the motor. Buy ether by the case, but it is expensive. Ether, butane, alcohol, or toluene could be used as a substitute for propane. Propane was used in this example because it will be widely available, while the other options would be difficult to obtain, or expensive to purchase in large quantity ahead of time. For small batches, ether is a practical choice.
Generally, the lighter in color the fuel is, the fresher it is. The darker gold in color is the fuel, is older fuel. As a rule of thumb, there should be plenty of good fuel mixed in with the old flat and smelly fuel to start and run the motor. Use the proportions in the example as a guide.
Blending Alcohol
In the case that someone happens to have a still that processes potatoes or grain into alcohol, mix in no more than 20 percent of 180 proof alcohol. (180 proof = 90 percent) with the old fuel to increase its octane rating. Alcohol increases the octane level (resistance to detonation) and can increase the octane rating of old fuel. If there is too much alcohol, then the air-fuel ratios would be too lean. If we are using only alcohol, we would need to increase the size of the jets, or artificially reducing the CFM (cubic feet per minute) by restricting airflow at the intake.
Operating Motors On Degraded Fuels
In cold weather there is less danger of heating up the cylinder head. If used in an automotive motor, if there is a distributor, retarding the timing will reduce excessive ‘knocking’. If there is a manual choke, we can adjust and riching up the air-fuel mixture manually, and this will reduce, or eliminate the knocking as well. In most modern fuel-injected motors, a ‘knock sensor’ would automatically retard ignition timing. To richen up the air-fuel mixture of an injection system, we could also partly block the air filter. If I had a chainsaw that was 30 years old, it would have a lower compression motor, relative to modern saws. If there was the risk of freezing to death, versus damaging the saw, I would certainly use this fuel in any available chainsaw, but I would not run this saw hard, and would often stop to let it cool. Ether, Propane, butane, or toluene, or a small amount of fresh fuel might still be needed to start the motor.
Running Motors in Extreme Cold Weather Using Degraded or Fresh Fuels
When I have just gotta start the saw in very cold weather using Avgas, I simply remove the cap on the saw, and turn a 1-pound canister of propane with a burner nozzle attached, and gently bubble some propane in. Or I’ll feed the propane into the air filter. Or use ether. Buy ether by the case now if you can afford it. [It is typically sold as “Engine Starting Fluid” at auto parts stores.] We can use ether or propane interchangeably. I am using propane because of its low cost. If we are using degraded fuel in cold or warm weather, or simply have a hard-to-start motor, this works. This can be done for fuels used in both 2-cycle and 4-cycle engines. It helps the engine start faster in extremely cold weather. Or if we plan ahead, or if we do not have access to ether or propane, we can bring the saw, generator or motorcycle inside, and let it warm up. As a liquid fuel, we can also use naphtha (white gas) to start the motor. Add a few drops into small motors directly into the carburetor after removing the air filter. Or use a bottle-fed sprayer, mist the fuel into the air filter of a fuel-injected engine, or carbureted engine.
I’ve been fooling with this sort of thing for a long time. I pulled off this dangerous stunt when I was about 14 years of age — you know, when I was young and dumb. A fire might have started from the oil and dirt sludge that typically becomes encrusted on the bottom of the crankcase oil pans. I should have cleaned off any combustible material. This incident occurred in Kalispell, Montana after a two-week spell with a low of -40F back in the early 1970s. I had to start a moving van with 30-weight oil in the crankcase. It was actually thicker than molasses, and more like wheel-bearing grease. The truck was started by heating the bottom of the oil pan with a propane torch and an electric hot plate, and with lots of ether down the carburetor.
In extremely cold conditions, heating up the oil allows the engine to turn over faster. Just as important, heating up the combustion chamber, creates the conditions whereby an air-fuel mixture better mixes, and ignites easier with a spark. Chemical reactions occur at a faster rate when higher in temperature. If it is man-portable, bring it inside for several hours, or better yet, overnight. Place in a location far away, yet within sight of a wood stove. This will allow the infrared heat (radiated heat) that is radiated by the stove to heat the motor, from a safe distance.
It the motor uses a battery-operated starter, turn the headlamps and the heater blower on for a few minutes, and then turn it all off, and let the battery rest for few more minutes. This will not waste power, but heat the battery internally and allow it to generate additional power. If this does not work, bring the battery inside and allow it to thoroughly warm up to well above freezing if possible, ideally 70 degrees F, or higher. It will take many hours to raise the internal temperature of the heavy lead plates inside. The older the battery, the warmer we need to get it. It will then have at least twice (or more) as much cranking power.
Fuel Storage
The best way to store any gasoline, either Avgas or Mogas, is in an air-tight metal can filled to the top. The standard military 5-gallon Jerry cans are the best. Purchase new seals for these old cans on the Internet. 5-gallon containers are the most practical for preppers. If a leak occurs then we have only lost the fuel in that container. And 5-gallon containers are the easiest to handle and lend themselves to transportation. For critical equipment such as chainsaws, if affordable, the engineered fuels, such as the Trufuel brand and others, that the manufacturer claims a 5-year storage life, is a great way to go. These fuels are likely from the same fuel stock that Avgas is made from. As a telltale, both Avgas and these expensive fuels are both light blue in color. I believe that these fuels are from the same stock. I’d rather save 75% off the lowest-priced engineered fuel, so I purchased lots of Avgas. Without a saw here in Montana, we could freeze to death. Pay the money and be warm. Avgas is the most economical choice for myself, and I was able to purchase many times more Avgas than I could if I had paid 75 percent more (per gallon) for Trufuel.
Also, we should know that oxygen degrades the fuel. This is another reason why I use metal U.S. Army Jerry cans as the best method for preservation. Even Coleman white gas stored in sealed metal cans loses it’s potency after many years of storage. The number of BTUs is noticeably reduced with the age of the fuel. BTUs can be crudely measured by timing how long it takes to bring one pint of water to a boil.
The same happens with all other gasolines. If we store gasoline in a partly filled container, or worse, a large tank, there is a reservoir of oxygen available to degrade the fuel. If stored in a plastic container, some plastics are oxygen permeable and oxygen leaches in through the plastic (polymer). Metal is best, and a Jerry can is designed to hold in fuel even during high peak pressures inside the container that occurs during summertime heat waves.
If an old Jerry can doesn’t seal well, then purchase a new gasket and tighten the lid. It is best to store these and other containers of fuel below ground and in well-ventilated and continuously shaded areas. Create a thermal break between the container and the ground to reduce the amount of condensation that occurs inside the container that often occurs when there is wide temperature swings during a change in the seasons.