Does Diesel Fuel Go Bad? Full Guide & Storage Tips

Diesel is used in many industries, from construction and farming to the military. Storing large amounts of diesel fuel enables you to refuel at will, but it also comes with a responsibility to monitor the fuel to ensure optimal performance. If you store diesel, you need to know the difference between good and bad diesel fuel to avoid damaging expensive machinery and equipment. 

The guide below explains the process of diesel fuel degradation, including how to identify bad diesel. Our list of storage tips helps you integrate your newfound knowledge into your existing storage practices to ensure the longevity of your investment. 

When diesel fuel monitoring becomes a burden, call on the experts at Cadence for the highest-quality fuel and service to match. 

Does Diesel Go Bad? 

Yes, diesel fuel goes bad if not burned within six to 12 months of acquisition. Diesel fuel’s shelf life is about twice that of unleaded gas, which remains stable enough for use for up to six months. Ethanol lasts an even shorter amount of time due to its organic nature. 

Unless you stockpile vast amounts of diesel fuel for your fleet or marine business, it’s unlikely you will ever need to worry about its shelf life. 

If you store a few cans of diesel fuel just in case your pickup runs out of gas, you’re more likely to use it within six months. It’s also a smaller amount to sacrifice if it degrades than an entire tank full of diesel fuel. 

Why Does Diesel Fuel Go Bad?

Diesel fuel is hardly a stable chemical — after all, its purpose is to ignite within the combustion chamber and provide power to diesel engines. However, oxidation, contamination, and degradation can prematurely shorten the lifespan of diesel fuel. 

Let’s talk about how these processes cause diesel fuel to go bad. 

Oxidation

Diesel fuel is a petroleum product that contains hydrocarbons as part of its chemical makeup. As time passes, these hydrocarbons interact with the oxygen naturally present in the air and break down the diesel fuel. Continuous or prolonged exposure to the air can cause the diesel fuel to oxidize and form sludge. 

Sludge is the nemesis of your diesel fuel system as it prevents the steady flow of fuel. As sludge gets picked up by the fuel pump and routed toward the engine, it can clog elements along the way, including your fuel filter(s), fuel injectors, and the fuel pump itself. 

If the engine becomes starved of fuel, the lack of consistency changes the air-fuel mixture and can lead to stalling and failure. 

Contamination 

Water and sediment can quickly contaminate diesel fuel and speed up degradation. Any type of watered-down fuel harms your engine, as water molecules resist compression and wreak havoc on internal engine components. The presence of water in diesel fuel can also breed bacteria and promote corrosion. 

Water is denser than diesel fuel, so it sinks to the bottom of your diesel fuel storage tank. As it passes over bare metal, it can cause the surface to corrode and weaken. Stagnant water is also ideal for microbial growth and can lead to a solid build-up of organic growth that acts like sludge. 

Sediment also settles at the bottom of your diesel fuel storage tank. Agitation can suspend these small particles and impurities in the diesel fuel and transfer them to your vehicle’s gas tank. 

Once there, sediment mirrors the damage sludge does to your fuel system, clogging small ports and fine mesh to impede the flow of diesel fuel. 

Degradation

Diesel fuel prematurely degrades in high-temperature environments and under direct sunlight. While exposure to heat helps diesel fuel combust in your vehicle’s engine, exposure to hot temperatures outside the combustion chamber accelerates fuel breakdown and causes unwanted chemical changes. 

As diesel undergoes this chemical alteration, the process reduces its efficiency and combustibility, which spells disaster for your car’s engine. 

What Are Some Signs of Bad Diesel Fuel?

Bad diesel fuel exhibits distinct visual characteristics and a foul odor separate from fresh diesel fuel. You can also identify degraded diesel fuel by performance issues. It’s best to identify bad diesel fuel before it makes its way into your car’s engine to minimize damage and expensive repairs. 

Fresh diesel fuel appears clear with a slight yellowish tint. Diesel fuel that’s been contaminated with water will appear cloudy. Excessive water content can turn the fuel milky and opaque. 

Diesel fuel emits a strong odor, but bad diesel fuel intensifies the scent with a sour or rancid note. Floating contaminants like diesel algae — sometimes called the diesel bug — can also accompany this strong smell. 

Sediment and sludge can be harder to identify since they sit at the bottom of the tank, but stirring the contents can help you quickly determine how much sediment is present by the change in translucence. 

If bad diesel fuel gets into your vehicle, it can cause numerous issues with telltale signs. If your vehicle emits excessive or white exhaust smoke, exhibits reduced power, or experiences a rough start or idle, bad diesel fuel may be the culprit. Bad diesel can also damage fuel injectors and significantly reduce your engine’s performance. 

What Are Some Storage Tips To Prevent Diesel From Going Bad?

Storing your diesel fuel properly can help extend its lifespan and maintain a dependable supply when you need it most. For businesses that rely on a steady fuel supply, bulk diesel delivery ensures you always have high-quality fuel on hand while reducing the risk of contamination and degradation.

Here are a few storage tips to keep in mind: 

• Proper storage containers: Place diesel fuel in steel or high-density polyethylene (HDPE) containers designed to hold fuel and seal it tight. 

• Temperature and location: Store diesel fuel in a cool, dark place out of direct sunlight and away from heat or ignition sources.

• Regular maintenance: Clean diesel storage tanks thoroughly, drying them completely before refilling them with diesel fuel. 

• Use of additives: Fuel additives help extend diesel fuel’s storage life and retard the fuel degradation process. 

• Rotating fuel supply: Use the oldest diesel fuel you have first before depleting newer stockpiles. 

• Quality monitoring: Monitoring your diesel fuel quality can ensure optimal performance and limit expensive repairs. Professional tank monitoring services can help relieve the burden and keep your outfit supplied with adequate diesel fuel. 

If you determine your diesel fuel is bad, dispose of it responsibly at a nearby hazardous waste disposal facility. Never dump old fuel down the drain or pour it directly onto the ground. 

Let Cadence Fulfill Your Fueling Needs 

Monitoring diesel fuel tanks can prove challenging, especially for extensive operations. Cadence’s tank monitoring and fueling services make it easy to have diesel fuel on hand without having to dedicate valuable resources to managing your fuel supply. 

Call us at 336-629-2061 to speak with a friendly and knowledgeable staff member about our innovative solutions and dedication to excellence that keeps America moving. 

Sources:

Ethanol Fuel Basics | Alternative Fuels Data Center

Diesel Bug 101 - What Is It? How To Avoid It | Conidia Bioscience

10 Reasons White Smoke Is Coming From Your Exhaust | MotorTrend

How to Dispose of Kerosene and Other Old Fuels from Home or Business | Hazardous Waste Experts