Shear flow instability is studied in multi-component plasma. The excitation of low frequency electrostatic instabilities in a collision less plasmas of two system of species (H+, O+, e−) and (H−, O+, e−) is studied. Inertialess electrons follow the Boltzmenian distribution. The massive ions (oxygen) and the light species (hydrogen) provide the inertia. Light ions may be both positive hydrogen as well as negative hydrogen ions. Many authors have generally neglected the low concentration of hydrogen ions in oxygen plasma of ionosphere, but we have pointed out that the hydrogen ions as impurity plays a significant role to increase the growth rate of ion acoustic wave (IAW). We study the effect of shear on the following two systems of species separately and then compare the results of two systems numerically. We observed that in presence of shear the growth rate of the system with negative hydrogen ion is larger than with positive hydrogen ion. Fluid theory is used to study the three cases of ion-acoustic perturbations with same shear flow, different shear flow and zero shear flow. The kinetic model is used to study the effects of electron current in presence of negative shear flow. Ion-acoustic waves (IAWs) can easily be excited and overflow the heavy ion Landau damping either by electron parallel current or sheared flows of ion species. Our results may helpful to solve possible applications of low frequency space and laboratory plasmas.