How Long Can Diesel Sit Before It Goes Bad?

Last Updated on July 17th, 2023

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In times of emergencies, there’s no access to a gas station. So you might need to store some extra containers of fuel. Many different types of fuels are used to power things; diesel is one of them. If you have a car or machine that takes diesel, having some could save you.

Diesel can usually be stored for up to 6-12 months if stored in the right conditions. However, if you want to prolong the life of diesel, you’ll need to add various stabilizers, which you can find on amazon or your local auto store. Doing this can extend Diesel to about two years.

How Can You Tell If Diesel is bad?

There are anecdotal stories of people claiming their fuel has lasted over ten years. While this sounds amazing, you risk destroying your generators and other machines if you use expired diesel. However, I can understand if there are no other options in an emergency situation.

If you need the generator and there’s nowhere else to stock new fuel, you might be left to hope that the diesel is still good. Here are some ways you can tell if your diesel has gone bad.

  • The diesel starts gelling or becoming sludge.
  • It’s becoming a darker color.
  • The fuel filters start clogging more easily.
  • If there’s a rotten smell
  • You start to see black smoke while it’s burning.

How to Stop Diesel from Going Bad?

You should add stabilizers and biocides to the diesel if you want to be able to keep it from going bad. Stabilizers are used to prevent oxidation within the fuel, which is the primary thing that will extend the life of the fuel. 

Biocides are a little more expensive than stabilizers, but they are an additive to prevent microbial growth. It’s recommended that you fill the tank with gas after putting the biocides in and circulate it to ensure it’s thoroughly blended. Then let it rest before use.


How Should You Store it?

Diesel is a very toxic fuel, so it’s essential you know how to store it correctly. Be sure to use gas-approved drums and check on them regularly for signs of corrosion or sediment at the bottom. If possible, try installing an in-ground tank instead to avoid water damage.

Diesel lasts longer if kept at a temperature below 70 degrees Fahrenheit, and that alone can extend its life for another few months. This is why diesel in Alaska lasts longer than in Florida.


How Do You Know if Diesel is Good?

While it’s good to know the signs that diesel has gone bad, you should also be able to recognize when diesel is still good. Be sure to keep your fuel away from water and condensation. Also, be sure there’s no contact with zinc or copper.

If you take the correct precautions, your fuel should be fine. Here’s a list of things to look for to make sure your fuel is still good:

  • The fuel looks clear and is not a dark color.
  • There are no sediments at the bottom of the container.
  • Pour some through a filter to see if anything catches.
  • If your machines work well with the fuel.


Can You Treat Diesel that Has Gone Bad?

Unfortunately, there’s no way to recycle diesel that has already gone bad. So if your fuel has turned into sludge, you have to throw it away and get new fuel. However, if you find a few years old diesel and want to polish it up a bit, there is a way to do it.

It’s a common practice in the Marines to rejuvenate old fuel by heating it, removing water, and reusing it in the ship. For home use, pour the diesel through a filter while rebottling it and add more biocides and stabilizers to be sure the fuel stays good for longer.


Final Thoughts on How Long can Diesel Sit Before it Goes Bad 

In times of emergencies, we might not have access to gas stations. Therefore, we need to stock up on fuels that can run our generators, cars, or other machines we might have. Diesel can last 6-12 months, but it can last for about two years if you add stabilizers and biocide.

Some say they’ve had diesel last for over ten years and that it never degrades. Of course, you’re risking your engines by using expired fuel, but you might not have a choice in tough times. Check for discoloration, consistency, and sediments to ensure your fuel is still good.

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