The knowledge of the viscous properties of crude oils is limited by the complexity and variability of the raw materials. Nevertheless, a Weissenberg number, defined by the product of the shear rate and the characteristic time of the considered system, allowed us to scale viscosities of both crude oil and mixtures of alkanes, at different temperatures. This characteristic time has its origins in the reorientation of oligomeric chains of alkanes along the flow direction. This reorientation is associated to an activation energy, which, according to the Adam-Gibbs theory, is correlated to changes of the configurational entropy.