This research explores the microbial biodegradation of used and unused power steering fluids (PSF), emphasizing the identification and isolation of bacterial and fungal communities and their contributions to biodegradation in pure and mixed cultures. Results revealed higher counts of cultivable bacteria and fungi in used PSF, linking microbial activity to degradation. Eight bacterial species were isolated, including Corynebacterium sp., Citrobacter sp., Bacillus sp., Serratia sp., Micrococcus sp., Pseudomonas sp., Shigella sp., and Staphylococcus sp., along with seven fungal species: Candida sp., Aspergillus spp., Penicillium spp., Fusarium sp., Cladosporium sp., Saccharomyces sp., and Mucor sp. Mixed bacterial and fungal cultures proved most effective at utilizing the fluid, evidenced by increased Total Viable Count (TVC), optical density (OD), and reduced pH, indicating hydrocarbon breakdown and acid production. When comparing PSF brands, fluids Abro Power Steering Fluid and Oando ATF Dexron II — largely derived from mineral oils—were more readily biodegraded than Sea Max ATF Dexron III, which contains more complex hydrocarbons. In summary, the findings highlight the critical role of bacterial and fungal consortia in PSF biodegradation, offering valuable insights for bioremediation and fluid management strategies.