Chlorella oil is rich in polyunsaturated fatty acids (PUFAs) like linoleic and linolenic acids, which enhance cold-flow properties but may lower oxidative stability of the biodiesel. Despite this, the oil’s high content of C16–C18 fatty acids ensures good transesterification efficiency and a decent cetane number. Biodiesel from Chlorella typically exhibits low viscosity and high combustion performance. Quality can be improved with antioxidants or blending with more saturated oils. With proper transesterification, Chlorella-derived biodiesel meets EN 14214 and ASTM D6751 fuel standards.