PRI-D is a super concentrated, complete fuel treatment that improves all diesel fuels and kerosene making them stable for multi-year storage. The “Sta-Bil” product is excellent for short-to-medium term storage of fuels for up to a year or maybe two. But PRI-D allows you to store fuel, especially diesel and kerosene, for up to five (5) years or more. Further, you can use PRI-D to “restore” tainted and aged fuels that were improperly stored. We recommend treating all long term stored fuels with PRI-D (or PRI-G specifically for gasoline).