RECYCLING AND CHARACTERIZATION OF SPENT ENGINE OIL USING TWO STAGES: SOLVENT EXTRACTION AND CLAY PERCOLATION TECHNIQUES. FJS [Internet]. 2023 Jun. 30 [cited 2025 Sep. 11];7(3):182-5. Available from: http://www.fjsadmin.fudutsinma.edu.ng/index.php/fjs/article/view/1836