The viscosities of argon, helium, hydrogen, krypton, methane, neon, nitrogen, and oxygen have been modeled using the friction theory (f-theory) for viscosity modeling in conjunction with the Peng-Robinson (PR) equation of state (EOS), Soave-Redlich-Kwong EOS, Stryjek-Vera modification of the PR EOS, and Mathias modification to the SRK EOS. The viscosity modeling has been performed at supercritical conditions and up to 1000 bar, covering most common conditions in industrial processes. The overall average absolute deviation for each fluid ranges from 0.4 to 1.4% and is in excellent agreement with the reported uncertainty of the recommended literature values. These results are obtained using only three friction constants and without any knowledge of the density. Further it has been found that the dilute gas viscosity can also be modeled using only three constants for each fluid, from the critical temperature up to 2000 K, within or close to the uncertainty of the recommended dilute gas viscosity data. The obtained results further show the application of the f-theory for viscosity modeling and its potential for applications to industrial processes.