A study was carried out on the antimicrobial activity of haloethers in M8 motor oil, which was determined by serial consecutive dilutions in sterile distilled water relative to gram positive bacteria (Staphylococcus aureus), gram negative bacteria (Pseudomonas aeruginosa and Escherichia coli), and fungi (Candida albicans). Meat peptone agar (MPA) with pH = 7.2 was used as the nutrient medium for the bacteria, while Sabouraud medium was used for the fungi. These compounds display bactericidal and weak fungicidal activity in M-8 motor oil and stop the growth of the microorganisms. These samples did not have a negative effect on the physicochemical indices of the motor oil and may be used as biocidal additives.