The shelf life of gasoline is one of the lurking problems with the prepper community. With this short article I will show you a simple process to take that lifeless gas and make it usable again.
One of the issues with very old (several years) gas is the formation of deposits and gum via oxidation. Ethanol doesn’t help either, except to line the pockets of the Ethanol Lobby.
Another issue is water absorption over time.
Gasoline is not one cut of hydrocarbons, but a mixture of light and heavy fuels. Over time the lighter elements [“fractions”] evaporate, leaving a fuel that can’t start an engine.
I’ll show you how to deal with all three major issues. Always be outside and downwind of any dwellings – and of course, no nearby ignition sources or flame.
The first step in refurbishment is filtration. Depending on the amount of gum and deposits, you first should filter through a rag placed in a funnel. Then pump it through a standard fuel filter – the kind found on a car. I’ve used a Mr. Gasket 12 VDC fuel pump for years without problem.
Water in gasoline can be nullified by Gumout. Keep plenty on hand.
The final step is adding in the volatiles that have evaporated away. An interesting fact is fresh gasoline is around 1% butane – that’s what leaves the storage tank first. You can safely and easily add butane or propane back into the gasoline without owning an oil refinery.
WARNING: What is described here are actions to take in extremis, a TEOTWAWKI situation. Only add butane to gasoline outdoors and downwind of any ignition source or dwelling!
Winter gasoline has a higher percentage of butane than summer products. The refinery does this to keep the vapor pressure higher on cold days.
The process to add butane / propane to gas is simple. Take a 1 lb. propane or butane container with regulator. Attach a gasoline-rated hose to the regulator which can reach to the bottom of your gas can. Slowly bubble the contents of the propane tank into the gas – the gasoline will readily absorb the butane / propane. The mixture ratio is 1:100, or a 1 lb. propane canister to 18 gallons of gasoline. A 20 lb. propane tank can refurbish over 270 gallons.
My friends and I did some experiments to validate this. The first was bubbling a small 2.5 oz butane lighter refiller into a gallon of gas in a clear container. I noticed that the butane bubbles hardly made it to the top level of gas; the gasoline hungrily absorbed the butane.
The second experiment was with four year old gas that was stored in a black tank. A large riding lawnmower simply refused to start with this old gas – a great opportunity to try the new recipe.
Propane from a 20 lb. container was bubbled through the gasoline to get to 1:100. After draining the lawnmower tank and refilling with the refurbished gas it started right up. There were no issues with how the engine ran, either.
If you are storing gas for prepping I would suggest these tips:
1) Use gas that does not have ethanol in it 2) Always use PRI-G in recommended dosages to pre-treat the gas, and also treat it every year thereafter 3) Keep the gas in a cool spot in a metal container. I use surplus stainless steel drums but carbon steel could work as well. (Plastic containers allow the volatiles in gas to leak out.) 4) Have a water absorber additive around as well.
Good luck! – Hugh F.
JWR Adds: Use extreme caution when handling gasoline. You will need to work in open air, well away from all structures and take precautions against static electricity sparks or other sources of ignition. (This includes any wands that you might try to use for injecting butane. And you will of course need to protect yourself with gloves from skin contact and protect your lungs from anything more than brief and incidental contact with vapors. Quite importantly, a couple of helpers should be standing by a short distance away with Class B or ABC-type fire extinguishers.
Do not attempt to bubble butane from a butane lighter into a container of gasoline unless you have first completely removed the striker wheel mechanism! As Hugh mentioned, using butane lighter refiller canisters and a wand would be far more practical and safe.
Older gasoline that has lost its butane and other highly volatile components (do some research on Reid Vapor Pressure) will often fail to start an engine, but that same gas will often run an engine, once it has been started. So be sure to stock up on several cans of ether-based starting fluid.
I’m not a chemist, so I don’t know whether propane will stay in solution in gasoline as long as butane does. But I suspect that butane must be superior in some way, since that is what the petroleum industry uses as a gasoline additive. Perhaps someone more knowledgeable can chime in.