Petroleum fuels, including diesel, are some of the most useful substances that have shaped our society. As important as diesel is, there is the question of its durability, as it tends to depreciate over time.
Does Diesel Go Bad? The quality of diesel tends to decrease as it gets older because of an accumulation of debris and microbes within the diesel fuel. Diesel also gets thicker with time, causing it to become less effective as a fuel.
In a technical review by some specialists who work with Chevron, the microbial growth that occurs within stored diesel fuel is a lot faster when there is water within the fuel.
How Long Does It Take for Diesel Fuel to Go Bad?
It has been shown through studies and research that diesel fuel starts to degrade and become contaminated after 28 days.
At temperatures of over 86 ° F (30 °C), diesel typically lasts for six to twelve months. When your diesel is stored for longer, sediments and gum are formed in the fuel after a while, when the fuel reacts with oxygen. Bad or rotten diesel fuel can lead to the buildup of soot in your engine, damaging your car or vehicle.
There is no expiration date for diesel. You can store your diesel for as long as you can, but the performance of your diesel will be significantly affected the longer you store it.
This means that the older your diesel, the more degraded it is. By the time, your diesel fuel is at the last stage in this degradation process, then your diesel has gone “bad” and there is nothing you can do to salvage it.
But why does your diesel go bad over time? Several factors and conditions affect how long your diesel in storage can remain top-notch. Some of these factors are explained below.
- Exposure to environmental variables creates chain reactions
Environmental factors like water, air, and heat are factors that adversely affect the performance of your diesel. When your diesel fuel is stored for a long while, it inevitably gets exposed to some of these environmental variables.
As a result, some chain reactions start to occur within the diesel fuel, leading to the fuel slowly changing its form. With time, these reactions lead to gummy, stained accumulations within the diesel.
- Darkening and Stratification of the fuel
As these chain reactions occur over time within the diesel molecules due to the environmental variables, the fuel begins to change appearance. Diesel gradually becomes darker and thicker, looking less like oil and more like sludge or gum.
Scientifically, these chain reactions cause a change in the molecular structure of diesel fuel. These reactions, coupled with the low sulfur content in modern diesel, cause microbes to grow in the fuel, creating biomass reactions over time. This whole transformation can create acids in the fuel that cause your fuel to break down entirely over time.
What Happens If You Use Old Diesel fuel?
You can use diesel after it has gone bad, but it might negatively affect the engine that it is used for.
If you use bad diesel for your vehicle or generator, it can result in internal vehicle damage and black smoke. Here are some issues that using old diesel can cause.
- The Sludgy Fuel will not burn properly, leading to blackened smoke
The sludgy, thick, and dark diesel fuel won’t burn as smoothly as good diesel that hasn’t been affected by environmental variables. This could cause black smoke to be produced and can also lead to sputtering of the engine, which is not good for your vehicle or generator.
- The poor lubricity of the diesel can cause internal damage to an engine
Bad and old diesel fuel is not as lubricious (smooth) as new, good fuel. The acidic nature and thickness of the diesel fuel that has gone bad can seriously affect your vehicle or generator’s fuel pump, injectors, and engine. In situations like this, you might not even be able to start the vehicle or generator.
- It can damage an engine’s piston
Using bad diesel fuel can cause damage to the vehicle’s piston during ignition. If this damage should occur, it can make it difficult to start your car engine, and it can reduce the performance of your vehicle when revving.
- Peroxides can eat away rubber and metal in the vehicle
During hot weather conditions, peroxides can form in the petrol, and this can eat away metal and rubber components within the vehicle. Vulnerable engine parts include copper in fuel pumps and the liner on fuel lines.
When you have stored your fuel for a long time without using special preservation techniques, environmental variables can cause damage to the vehicle, and they can result in any of the above-mentioned side effects on your vehicle. Thus, when your diesel fuel is old and damaged, it is important to consider disposing of it legally and safely to prevent damage to your vehicle.
What Is the Longest Lasting Fuel?
| Fuels | Lasting Time |
| Gasoline | Less than 12 months |
| Diesel | 18-24 months |
| Propane | Indefinite |
| Natural gas | Indefinite |
| Solar | Indefinite |
| Firewood | Indefinite |
| Alcohol | Indefinite |
| Kerosene | 5 years |
Propane, alcohol, wood, and charcoal are examples of good emergency storage fuels that have a lengthy shelf life and can be stored indefinitely while retaining their excellent quality.
There are some reasons why long-lasting fuels are an important accessory. For instance, preparing for emergencies usually involves finding a fuel that stays good for long, and this search can be daunting.
You never know when a disaster will strike, and you won’t want to be caught off-guard with a fuel that will go bad quickly. Thus, you should find fuel with a long shelf life for the best experiences.
Here are some great fuel sources and their life span.
Fuels that are said to have indefinite shelf lives are those that can last “forever”. These fuels will never go bad if you provide them with the ideal storage environment. Here are some of these special fuels and their appropriate storage conditions:
- Alcohol
Alcohol is a good fuel with indefinite shelf life when stored in a cool, covered container. Once alcohol gets exposed to the environment, it starts to evaporate and loses its potency. Thus, it is important to store alcohol in a closed environment.
- Firewood
Dry firewood is another fuel with an indefinite shelf life. Technically, you can store firewood for an unending period if you store it properly. However, the output energy of firewood when burned tends to decrease as it gets older.
- Natural Gas
Natural gas is an example of a fuel type that can last “forever” if stored under the right conditions. Natural gas is also a great option in case you experience a power outage. However, it might not be appropriate for you to store copious amounts of natural gas at home since it needs delicate handling.
Whenever you have a choice to make, all factors being equal, always select the fuel with the longest usable shelf life. However, the purpose that you have in mind for the fuel can affect what fuel you choose, limiting your options. In such situations, there are some special ways to boost the lifespan of your fuel, ensuring that it lasts for much longer than it usually will. Some of these procedures are highlighted in the heading below.
How Do You Keep Gas Fresh for Years?
The best way to ensure that your gas is kept fresh for as long as possible is to ensure that you store it properly.
The storage of gas is quite straightforward, as it needs to be stored in a tightened cylinder in a cool environment.
Other fuel types are more delicate since there are various container types for liquid fuels. Depending on the volume of your diesel, you could store your diesel in either a drum or a tank. If your fuel is about 55 gallons or below, then storage in drums is best.
To ensure diesel lasts in drums, here are some tips.
- Ensure water does not touch the drum. This could corrode the drum and can affect the diesel fuel in it.
- Keep the temperature consistent. Fluctuations in temperature can cause condensation and water accumulation. None of these is good for your fuel. To ensure your diesel fuel lasts long, consider sheltered storage.
- Clean drum between filling it. Before putting diesel into a drum, it should contain no dirt.
If you, however, have a larger amount of fuel to store, tank storage would be your best option. The good thing about tanks is that they have a drain at the bottom. Thus, if bacteria, water, or sludge settles at the bottom of your tank, you can easily drain them off.
Below are some tips to make the fuel in the tank last longer.
- Consider an underground tank. The cost of building an underground tank would be expensive but it is a worthwhile investment. An underground tank will keep your fuel free of water and maintain a constant temperature.
- Keep the tank full. The more space there is above your tank, the more room there is for condensation and for bacteria to thrive.
- Insulate tanks. Wintry weather can cause ice to form in your tank. Insulation of the tank will prevent this.
- Clean your fuel regularly. Watch out for signs of the diesel going bad, like gelling or scum. When this happens, let the fuel sit, so the scum goes to the bottom of the tank. Then, drain the fuel to rid it of all contaminants.
For long-term diesel storage, there is only so much that using proper storage can do to ensure your fuel is in the best possible condition. To ensure your fuel lasts, if possible, you will need to implement these additional practices.
- Biocides
Microbial growth is one of the major causes of diesel going bad. Diesel biocides are added to prevent microbial growth. Look at the BIOBOR JF and take preventative measures now!
Learn more about the BIOBOR JF and see how it can save your diesel here!
- Stabilizers
These are added to prevent oxidation and acid-based reactions that can cause your fuel to go bad. They can extend the growth life of your fuel by years.
Check out this highly rated fuel stabilizer, PRI 32-D on Amazon. Learn more here!
- Water Absorbers
These additives find water molecules in your fuel and bond with them. This bonded water is trapped in your fuel and thus burns off as steam instead of spoiling your fuel.
By using proper storage (using either drum or tank as discussed above) and any of the further practices mentioned, you can prevent your fuel from going bad for as long as possible.
Look below for some extra storage information!
How Can You Tell If Diesel Fuel Is Bad?
Most times, you can tell that your fuel is bad by just looking at it. The discoloration that happens in bad diesel is often visible.
Sometimes, just looking at diesel might not be enough to tell if it has gone bad. In many circumstances, you can expect your diesel to last for about six to eight months, but if you still want to confirm whether your diesel is usable, here are symptoms to watch out for.
- Darkening and thickening of fuel.
- Shortening of fuel filter life.
- Degradation of fuel during operation.
- Emission of stench from the fuel tank.
- Corrosion of fuel injectors
- Increase in exhaust smoke
- Floatation of smoke and sludge in the fuel tank.
If you notice any of the above-listed symptoms in your fuel, it is a sign of microbial and fungal contamination, and you need to either rejuvenate your diesel (if possible) or discard it legally and appropriately.
How Do You Rejuvenate an Old Diesel?
You can rejuvenate oil diesel by filtering it, decanting off the water content, and adding a fuel reconditioner to it.
When your diesel fuel is getting bad, some techniques can be used to rejuvenate the fuel and restore it to the best possible condition.
Here are some common steps.
- The fuel is pumped through a filtration unit.
- The filtration unit is heated to help with the filtration.
- Water is decanted off to the barest minimum.
- The fuel is now rid of water, and consequently (due to the application of heat), all microbes and fungus in the fuel are killed, stopping microbial and fungal growth.
However, prevention, as they say, is always better than cure. Here are some ways to ensure your diesel does not go bad at all.
- Purchase only high-quality fuel always.
- Clean and inspect fuel tanks at regular intervals.
- Use additives to stop microbial and fungal growth.
- Drain water off the fuel and out of the tanks regularly.
