This NREL/DOE study studied the properties necessary to store B100 up to 1 year and B5 and B20 up to 3 years. The study shows that adding antioxidants after the onset of oxidation is effective at restoring stability, and that biodiesel blends are shown to be stable for 3 years in suitable storage conditions.

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Screencap - Long-term storage stability of biodiesel and biodiesel blends