Diesel fuel oxidizes over time if stored. Its shelf life is limited by the formation of gum and sediment that can clog fuel filters and injectors in an engine.
At 68 degrees Fahrenheit, the shelf life of diesel is at least 12 months. Above 86 degrees Fahrenheit, its shelf life ranges from 6 to 12 months, according to British Petroleum. Diesel also breaks down more quickly if stored in contact with water, as well as metals like copper and zinc.
The shelf life of diesel can be extended by keeping storage tanks full to prevent water from condensing, periodically filtering the tanks, replacing the fuel regularly, monitoring it for sediment, and having it tested at a laboratory.
Using additives can also prolong shelf life. Diesel additives include antioxidants that prevent sedimentation, fungicides and biocides that prevent microbial contamination and metal deactivators for zinc and copper.
