A single consistent correlation, based on Walther＇s equation, is described and used to estimate the kinematic viscosity-temperature behavior for undefined petroleum fractions. The correlation requires a minimum of experimental information, with a minimum number of correlation constants. When a single viscosity measurement is used as an input, the described correlation is shown to be more flexible and gives results comparable with those of previously published correlations. When the boiling point and the specific gravity are available as input, the correlation is shown to give better results than other published correlations.