Hydrodynamic lubrication is definitely one of the foremost factors upon which the load carrying capacity within journal bearing mainly rely. Therefore, maintaining journal bearing lubrication away from boundary and transient lubrication regions is so instrumental in avoiding journal bearing wear. Accordingly, Universal Journal Bearing Test Rig (UJBTR) was specifically used for conducting wide range tests related to the versatile operational parameters utilizing different oil grades. Those were examined at the variable shaft speeds from 300 rpm up to 600 rpm, under the different applied loads from 50 〖kg〗_f up to 510 〖kg〗_f. The derived results were verified theoretically, where the error percentage hasn't exceeded 5.9 %. In light of the conducted study, oil film pressure was assured to rise with the increase of oil viscosity, loads, and speeds. For more detailed discussion, a dimensionless analysis was carried out to identify the impact percentage for viscosity, speed, and load on the hydrodynamic lubrication. It is observed that increasing load by 60 % had a considerable impact regarding the coefficient of friction where it reduced by 89 %. However, it turned out to have very negative impacts on hydrodynamic lubrication, where the hydrodynamic lubrication has moved into the hazardous boundary lubrication region. Based on the derived outcomes, operational factors are crucial impacts that shape journal bearing behavior considerably in real operating conditions either positively or negatively. Consequently, much consideration must be given to the selection of such factors so as to maintain and possibly enhance journal bearing performance.