A six parameter Quartic equation of state (QEOS) is presented in this work to explore the scope of a non-cubic equation of state for the prediction of thermodynamic properties and analyze its improvement over the commonly used cubic equations of state. The QEOS uses 4 compound specific parameters in addition to the critical constants. The QEOS predicted results for various thermodynamic properties are compared with experimental data and with results obtained from Ghoderao-Dalvi-Narayan (4PGDN1) equation of state. The QEOS fits data best when it most resembles a Cubic EOS (CEOS) obtained by setting one compound specific parameter e to nearly zero. This presents an opportunity to use the CEOS for practical calculations while using the theoretically more correct QEOS for theoretical analysis.