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Abstract-Biodiesel is a renewable energy, possesses high cetane number and flash points, resulting in its suitable uses in diesel machines and its safe distribution and storage, as well as low gas emission, and its function as lubricant. Disadvantages of the biodiesel include its high density and viscosity, resulting in plug and ineffective injection system, and low oxidation stability. This research studied about antioxidant additions to maintain oxidation stability of biodiesel. Induction period (IP) measuring kit, to measure oxidation stability, was constructed by using modified Rancimat principle. The best operation conditions were at temperature of 110 0 C and pressure of <100 Kpa/h, resulting in relation coefficient (r) of 0.996 and detection limits of 6.54 ppm of oil samples. Palm fatty acid distillate (PFAD) used contains free fatty acids (FFA) of 86.43%. The IP of the biodiesel was only 1.7 hours. The optimum concentration of pyrogallol (PY) antioxidant added into biodiesel was 20 ppm whereas of propylgallate (PG) was 40 ppm. At these concentrations, the biodiesel IP increased to become 7.1 and 6.5 hours, respectively. Additions of these antioxidants fulfill the IP requirement of biodiesel measured by European Standard of EN 14214 (> 6 hours).