How to Recondition Old Gasoline on Your Own

One of the smartest things that you can do as a prepper is to ensure you have plenty of gas on hand in case of an emergency.

From fueling your personal vehicle to running needed generators when the grid is down, your own supply of ready to use gasoline can make all the difference when the situation is otherwise totally out of control.

But gasoline, as a fuel, has one fatal flaw for this purpose: it degrades steadily over time, losing potency before eventually going bad entirely.

At best, this means you might be forced to deal with malfunctioning equipment, or unable to use it at all. At worst, old gas that has gone bad could damage or destroy an engine!

Naturally, this means that storing enough gas to be worthwhile and rotating it continually so it doesn’t go bad is a job in and of itself.

However, you should know that it is possible to recondition old gasoline if you know the proper procedure and have a few special additives. This can make your life easier when it comes to storage, or even save the day when you are in a crisis.

Keep reading, and this article will tell you everything you need to know.

Does Gasoline “Expire?”

This might be a surprise to some readers, and especially to beginning preppers, but gasoline can in fact expire.

Now, to be really technical it doesn’t expire in the same way that food in our pantry or refrigerator expires, by going rancid, but it does go bad over time for a couple of different reasons.

One of these reasons is that the volatile compounds that make gasoline a usable fuel begin to oxidize and lose potency.

Very literally, this means the gasoline provides less “pop!” The other way that gasoline goes bad is specific to modern gasoline-ethanol blends, the typical stuff you get at your local gas pump.

The two components are very much like oil and water, and over time they will separate, permanently ruining the fuel.

Either of these outcomes can be a showstopper if you are depending on your stored gasoline in an emergency, but for our purposes it is only possible to reverse a loss of potency by oxidation, or to potentially halt or slow the separation of components in gasoline-ethanol blends.

But, the first step in the reconditioning process is determining whether or not the gasoline can be saved in the first place.

Trying to recondition gasoline that is too far gone is just throwing away good money after bad, and will still likely wind up damaging your engine. The next section will help you figure that out.

How Can You Figure Out if Your Gas is Savable?

Like I mentioned above, the first step in the process of reconditioning your gasoline is determining whether it is just old and a little stale, or if it has truly gone bad and is no longer salvageable.

Properly assessing the condition of the gas can mean the difference between success and failure, and a potentially damaged engine, so you’ve got to get this right.

Now, the good news is that you don’t need to be a chemistry major to figure this out. All you need is a working set of eyeballs and a couple of clear glass beakers or jars that will allow you to examine the gasoline closely after you take a sample.

We will be looking at the color of the gasoline, the appearance of any distinct layers or differences in transparency in the liquid, the presence of sediment or other solid contamination and the consistency of the gasoline.

Take a sample of your stored gasoline and a sample of new, known fresh gasoline and then assess your stored supply against the following:

Darkening or Reddish Color- Gas that has been stored for a while is likely to darken compared to the fresh stuff, but you want to be alert to any notable red or brown-red color in the liquid.

The redder it looks, the worse off it is because this means the components of the gas have started to break down into a varnish like material that can clog your engine. If it is a little dark or just a little red, the gas can be reconditioned.

Cloudy, Milky Appearance- Gas that has turned opaque or only vaguely translucent has either broken down severely or been contaminated by the container it is in. You can’t save it, so don’t try to recondition it.

Slime or Film- The presence of any sort of sludgy film or slime is another surefire indicator of serious contamination that you will be unable to treat. Discard the gas, you cannot recondition it.

Particles and Sediment- Floating particles or bits of material is another major warning sign that the gas is in bad shape, though it might be possible to filter them out and then recondition the gas normally if it does not appear cloudy, slimy or too red.

Assuming you have the means to strain out the particles completely and the gas looks decent otherwise, you can recondition it.

Noticeable Layering- A problem that is typically inherent to gasoline-ethanol blends, this is known as phasic separation and occurs when this type of gas gets too old. If the gas sample has an appearance that looks like oil floating on water, you cannot recondition it.

Note: If you are examining pure gasoline, this likely indicates the presence of water contamination and you may or may not be able to recondition it depending on the severity.

Can Gas Be Too Old to Save?

Yes, it can. Gasoline that gets way too old, be it pure gasoline or a gasoline-ethanol blend, can completely fail to function in an engine, necessitating a costly and lengthy tear down to remove it and clean the engine.

Another outcome is that it can gum up the works of the engine, impeding performance and causing knocking, sputtering and other malfunctions. Fuel injectors are particularly vulnerable to old, gummy gasoline.

This is why it is so important for you to assess your gasoline supply before you ever set out to recondition it.

Here’s How to Recondition Your Gasoline

All you’ll need to recondition your old gasoline is a quantity of new, fresh gasoline. By mixing in the new gasoline with the old, you can give the resulting mixture enough volatility that it will function the engine more or less normally, although it might run a little rough.

That’s really all there is to it, although as you might imagine there are some specific steps that should be followed for best results.

Ideally, you will have an empty fuel can or other container to mix the gasoline in. If the old gasoline is in a fuel tank, know that the tank must be at least half empty in order to have room to add new gasoline. If the tank is totally full of old gasoline, you’ll need to drain some of it off to make room for the new.

Use the following procedures to recondition older gasoline that is not too far gone.

Step 1: Determine Ratio

If you are reconditioning older gasoline that is still definitely serviceable, you’ll want to add the new gas to the old in a 50/50 ratio.

If you are dealing with very old gasoline that is just on this side of questionable, the mixture should be 75/25 new gas to old gas.

Step 2: Add New Gasoline

Carefully pour the new gasoline into the can or tank containing the old gasoline. Remember to follow my advice above, draining off some of the old gasoline to make room for the new if you are pouring directly into a fuel tank.

Step 3: Mix It

Now all you need to do is mix the gasoline by gently rocking or sloshing the fuel can, or carefully rocking the tool, generator or vehicle back and forth.

Do this for a couple of minutes to make sure everything gets fully blended and incorporated. If you are mixing in a container, you might consider using a clean, completely non-conductive tool to stir the gas together.

Step 4: Try to Start Vehicle or Tool

Time to try the starter. You should expect a decrease in performance and don’t be discouraged if the engine doesn’t start right away.

Give it a few tries and see if you can get the engine going using your reconditioned gasoline. Once it does, let it idle and warm up a little bit and if possible run it more gently than you would normally for best results.

And that is truly all there is to reconditioning gasoline. Assuming that your gasoline, whatever kind it is, is not too far gone it is possible to bring it back to life using a quantity of new, fresh gasoline.

Now, because result of the mixture does have lower octane than is ideal it won’t run with maximum efficiency, but it will run and that might make all the difference in your situation when you are in a bind.

That being said, there is more to do if you want to maximize your chances of it safely and effectively using old gasoline. The following sections will tell you more.

Should You Risk Using Old Gas in an Emergency?

Learning all of this, a question that is bound to be on the mind of many readers is whether or not they should risk using old gasoline at all in an emergency. The answer is, as always, “it depends.”

If your “emergency” is just running behind on a job or potentially having to work past quitting time because you need to go to the station and draw fresh fuel, it’s almost certainly not worth it.

A little extra time to prevent the risk of damaging or destroying an engine is a good trade.

But, if you are in a life-threatening situation or a long-term survival scenario where supplies are limited or nonexistent, that old and questionable gasoline might be very precious indeed.

Likewise, if lives are on the line and the outcome is going to be determined by whether or not you can get that motor turning over, you are probably advised to try that old fuel and hope for the best.

Of course, you should take a few minutes to blend it with fresher gasoline if time permits!

Consider Using Fuel Additives to Improve Performance

Reconditioning old gasoline using fresh gasoline is only part of the puzzle. There are other things you can put in your gas to improve performance and reliability, both when it is going into storage and when you are taking it out of storage.

Fuel Stabilizer Additives

Ounce for ounce, one of the best things you can purchase for your standby supply of gasoline is a fuel stabilizer, with one like StaBil being an old and trusted product.

These fuel stabilizers do exactly what they say: they prevent the fuel from breaking down, or rather they greatly slow the process, allowing you to get a much longer shelf life out of your stored gasoline.

Depending on whether you are starting with a gasoline-ethanol blend or pure gas, you can get an extra 6 months or an entire year out of your stored gas using these additives as directed.

It’s a small investment for a lot of peace of mind, and it will save you a ton of time in the bargain when it comes to rotating your gas.

Detergent Additives

Another good choice is a detergent additive if you are working with older gasoline that you are trying to recondition yourself.

If you are dealing with older gas that is still clear, and dark and red but not too far gone, these are a great inclusion to help protect your engine.

These detergents can help prevent those sticky, broken down compounds from adhering to the components in your engine which can cause a loss of efficiency and eventually malfunctions.

Keeping a supply of detergent additive handy to be mixed in with your reconditioned gasoline after the mixing phase described above is very cheap insurance if you’re going to roll the dice with some old gas.

Frequently Asked Questions

What’s the best way to filter gasoline with sediment in it?

Filtering contaminated gas should never be done lightly since failure can damage your engine.

The best way to do so is with a specially designed filter apparatus for the purpose, but an improvised solution using a clean cloth, fine metal sieve and finally a coffee filter or similar paper can work.

Is it possible to fix ethanol gas that has separated?

In my experience, no. Gasoline-ethanol blends are troublesome, and once they start to separate they are usually too far gone to fix with additives or anything else.

Can you recondition gas with oil additive?

Yes, potentially. The presence of oil in the gasoline is another variable that must be accounted for. Consult the information sheet on the oil additive or contact the manufacturer for more information.