A viable alternative to fossil fuel diesel is biodiesel. Due to its high oxidation risk, low stability, and short storage life, biodiesel has significant downsides. We use biodiesel-compatible antioxidants to eliminate issues. Sustainable energy and biodiesel antioxidants impact the global economy and environment. Researchers built Schiff bases to examine biodiesel-diesel blends. Schiff bases deactivated metals and antioxidants. Compound structures were disclosed by TLC, MP, FT-IR, 1H–13C NMR, and elemental analysis. These compounds' antioxidant activities were investigated utilizing the DPPH• free radical trapping and ABTS•+ radical cation scavenging assays. The study utilized 30% biodiesel, 70% diesel. Mixtures of 3000 ppm Schiff bases were tested for oxifast. Comparison to BHT antioxidant. Sample names were D100, B30D70, B30D70BHT, B30D70_2, and B30D70_1. These samples were characterized by FT-IR, DSC, and TGA. The DSC measured sample crystallisation temperatures. Antioxidant-rich diesel was lower than D100. DSC testing indicated antioxidant strengths of -11.76, -11.87, -12.03, -12.73, and -13.97 °C at crystallization for samples D100, B30D70, B30D70BHT, B30D70_2, and B30D70_1. TGA values of 102.30, 118.06, 129.84, 131.75, and 137.01 indicate sample stability increases Tonset. Antioxidants clarify FT-IR spectrum antioxidant impact areas. The extra antioxidant works. In various dosages, Schiff bases increase biodiesel's oxidative stability.