How to Avoid Common Diesel Fuel Contamination Issues

Diesel fuel contamination is a major problem that can lead to unplanned downtime, higher maintenance costs, and serious equipment damage. If you’re managing fuel storage or fleet operations, clean diesel should be a top priority.

Contaminants can sneak into tanks more easily than you’d think, and they don’t take long to multiply once they get inside. Knowing how contamination happens, how to catch it early, and what steps to take is the key to keeping your operation moving forward.

What Causes Fuel Contamination?

Most contaminants in diesel fuel come from a handful of sources. They tend to enter diesel fuel through improper storage, exposure to moisture, and degradation over time. The most common types of diesel fuel contamination include:

• Water intrusion: Water is one of the biggest threats to stored diesel. It can enter tanks because of poor storage or handling techniques, such as exposing the diesel to wide temperature swings or leaving the tank partially filled for long periods. The resulting condensation or leaks contaminate the fuel.
• Microbial growth: When water is present in diesel fuel, microbes flourish. While sometimes called “algae,” this contamination in diesel fuel is comprised of bacteria or fungi. These microbes form slimy deposits that clog filter, release corrosive acids, and reduce combustion efficiency.
• Sediment: Rust flakes, dirt, and debris from aging tanks or dirty fuel sources settle at the bottom of your storage tanks. Every time fuel is agitated or drawn from the bottom, that sediment gets pulled into the engine, wearing down and clogging internal components.
• Oxidation: Diesel fuel naturally degrades over time, especially when exposed to air or heat. As diesel oxidizes, it forms sticky residues and sludge that gum up filters and leave behind deposits in tanks and engines.

What Are the Signs of Diesel Fuel Contamination?

Learn to recognize the early signs of contaminated diesel fuel so you can correct it quickly. Here’s what to watch for:

• Hazy fuel: Diesel should be clear and bright. If it looks cloudy or milky, there’s likely water, microbial growth, or oxidized fuel in the mix.
• More frequent filter changes: Clogged filters are another diesel fuel contamination problem. If you’re changing them more often than usual, it’s time to investigate your fuel quality.
• Poor engine performance: Contaminated fuel leads to rough start, misfires, power loss, excessive smoke, or stalling. If engines aren’t running like they used to, the fuel may be to blame.
• Corrosion: Water and bacterial contamination lead to rust inside tanks, fuel lines, and fittings. If you notice equipment is corroding, it’s time to assess the fuel.
• Unusual odors: Diesel contaminated with bacteria often gives off a sour or rotten smell. It’s worth looking into if your fuel smells different than usual.
• Presence of water: Free water collecting at the bottom of the tank, which you can detect using a simple in-tank paste test, is a sign of contamination in progress.

How to Prevent Contaminated Fuel

Diesel fuel contamination problems are a real headache, but fortunately, they’re easy to avoid. Adopt these consistent habits to keep fuel clean, reliable, and safe for long-term storage and use:

• Test fuel regularly: Routine diesel fuel contamination testing helps spot problems before they cause breakdowns. Use basic tools like dipsticks and water paste or send samples to a lab to check for water, bacteria, and oxidation.
• Keep tanks full and sealed: The more air in your tank, the more condensation can form. Keeping tanks topped off reduces moisture buildup. Always check that caps, seals, and vents are in good condition and tightly closed.
• Install and maintain water separators: Water separators capture moisture before it reaches your engines. Make sure they’re emptied and serviced regularly to keep them working as they should.
• Schedule tank cleaning or fuel polishing: Tank cleaning removes sediment and sludge, while fuel polishing systems circulate and clean the fuel without needing to remove it from the tank. These services extend fuel life and keep storage systems working efficiently.
• Use stabilizers and biocides: Stabilizers slow fuel degradation, and biocides eliminate bacteria and fungi. Use these treatments according to the age of your fuel, the condition of your tanks, and how long the fuel will be stored.
• Rotate fuel stock: Diesel doesn’t last forever. Follow a first-in, first-out rotation policy to ensure you’re using your oldest fuel first. Avoid storing fuel for longer than 12 months without treatment or monitoring.
• Inspect tanks for water: Check your tanks monthly. Look for signs of condensation buildup or leaks during your inspection. If you find problems, resolve them immediately to avoid microbial growth and fuel degradation.
• Train your team: Everyone who handles fuel should know how to inspect it, recognize signs of contamination, and follow proper storage and delivery procedures. After all, fuel handling isn’t just about pumping, it’s about protecting your equipment and promoting up time.
• Partner with a reliable distributor: Contamination can occur during delivery if hoses or tanks are dirty. Choose a diesel distributor who filters fuel, maintains their equipment, and takes quality seriously. For even stronger protection, go with a company that also provides fuel testing, additives, tank cleaning, and support when issues arise.

Protect Your Diesel Supply with Red River Oil Company

Clean, reliable diesel fuel starts with the right partner. With over 100 years of combined experience, Red River Oil Company is the top choice for locally owned service and custom fuel plans. We have four facilities in Ashdown, Texarkana, Foreman, and Idabel, allowing us to serve operations of all sizes across Texas, Arkansas, Oklahoma, and Louisiana. Contact us today to schedule reliable fuel delivery or get more tips to protect your supply.