Study of Viscosity and Density Changes of Waste Cooking Oil Biodiesel Due to Gradual Heat Treatment. ENERGY: JURNAL ILMIAH ILMU-ILMU TEKNIK, [S. l.], v. 15, n. 1, p. 1–12, 2025. DOI: 10.51747/energy.v15i1.1511. Disponível em: https://e-journal.upm.ac.id/index.php/energy/article/view/energy.v15i1.1511. Acesso em: 11 aug. 2025.