<p>Entropy generation (EG) is vital for understanding fluid flows as it quantifies the irreversibility of processes, indicating energy that cannot be used for work due to factors like friction and heat transfer. High EG can lead to energy losses and decreased efficiency, making it important for engineers and scientists to analyze and minimize these effects. By minimizing the EG, we can optimize the efficiency of fluid systems and enhance performance in engineering applications such as cooling systems and heat exchangers. The main theme of the present investigation is to investigate the irreversibility in bioconvective engine oil-based HNF flow under the influence of magnetic field. The effects of surface porosity and inertial forces are accounted through Darcy–Forchheimer principle. Energy equation is formulated considering dissipation, heat source, Dufour effects, Joule heating, and thermal radiation. Mass concentration relation is developed through the presumptions of activation kinetics, Soret features, and chemical reaction. The phenomenon of bioconvection generated due to the addition of gyrotactic microorganisms in engine oil is further accounted. The mechanisms of thermal and solutal convective edge restrictions are considered. The irreversibilities are formulated using the second thermodynamics law. The formulated dimensional governing equations are altered into system of ordinary equations and then treated through the NDSolve function of Mathematica. The consequences of diverse flow-regulating variables are examined. Physical quantities are investigated numerically. Additionally, a comparative study is presented for mono nanofluid and hybrid nanofluid.</p>