High pressure viscosity characterization of four vegetable and mineralhydraulic oils

In the long term, environmental friendly oils from renewable sources seem to be the more realistic pathto a sustainable future for the industry regarding the lubrication issue. Vegetable bases for lubricants havebeen studied in the last decade in order to analyze their potential industrial applicability. Their strengthsand weaknesses are already known and thus, the next step is to study how the final mixture of vegetablebase plus additives might perform in comparison to lubricants used in actual machinery. Here, we presentthe results obtained for the viscosity behavior of two hydraulic mineral oils and two vegetable oils for-mulated to substitute the mineral based ones. The measurements were taken at three temperatures:313.15 K, 343.15 K and 363.15 K and at pressures up to 250 MPa using a high-pressure falling-body vis-cometer. To address the performance of these oils in the elastohydrodynamic lubrication regime, we alsocalculate the universal pressure-viscosity coefficient, ˛film, and the temperature-viscosity coefficient, ˇ.