This investigation compared tensile strength, stiffness and deformation of White Safari, Opeper and Bush Mahogany under untreated and used-engine-oil-treated conditions. Wood obtained in Calabar, Nigeria, was prepared, cleaned and sanded before treatment. The oil was filtered and treated specimens were immersed for six hours. Three specimens were tested for each of nine conditions (27 specimens in total), and the available tensile results are reported as condition means. A universal testing machine operated at 30 mm/min with a 1 N pretension. The highest reported mean peak stress was 64.998 MPa for Bush Mahogany condition MATKD, 16.82% above its untreated reference (55.639 MPa). Untreated White Safari showed the highest reported modulus (2103.601 MPa), while untreated Opeper had the greatest strain at peak (9.067%). Treatment-associated changes differed markedly between species: both treated Opeper conditions showed lower peak stresses than the untreated reference, whereas the White Safari conditions showed higher peak stresses but lower moduli. Strength, stiffness and deformation therefore did not improve simultaneously. Only consolidated means were available, preventing estimation of specimen-level variability or statistical significance. The findings provide a descriptive basis for further replicated investigation with archived specimen-level results, moisture control and measured treatment retention; they do not establish structural suitability or environmental safety.