Thermal, spectral, oxidation stability and antioxidant behavior on Group II base oils

• A decrease in average chain length among the paraffinic oils increases the viscosity index (VI).
• Lower naphthenic (Cn) carbon content increases the oxidation stability.
• Increase in iso-paraffinic (Cip) carbon content increases the thermal stability.
• Addition of antioxidant remarkably enhances the oxidation stability of the base oils.

Due to constant increase in the demand for highly saturated Group II and Group III base oils and their application in use as special lubricants, it is a must to have a clear picture of structural distribution of base oils. In this study, pressure differential scanning calorimetry (PDSC), rotary pressure vessel oxidation test (RPVOT), kinematic viscosity (KV), Noack volatility and elemental analysis as physico-chemical tests are studied for Group II base oils. The inferences derived from these analyses established the relationship between the chemical structure and selection of the base oils to meet future product specifications. 1H and 13C NMR (Nuclear Magnetic Resonance) data had also been used to generate average structural profile and it was used to account for the oxidation stability of the selected base oils.