The frequency dependence of the proton longitudinal relaxation time T1(ω), and the ratio of relaxation times at a given magnetic field strength T1/T2, have been discussed as parameters to relate the molecular dynamics and the composition in crude oil. The broad distribution of both relaxation parameters as a consequence of the multitude of components in crude oil has been addressed by means of deriving suitable averaged parameters. In the presence of asphaltenes, however, this approach turns out to be problematic since the spread of, in particular, T2 is increased, and the distribution of T1(ω) varies with frequency. One possible reason for this observation is the suggested increased interaction strength of aromatic molecules with the polycyclic asphaltene cores since, in these oils, the signal is obtained solely from the mobile fraction of molecules (maltenes) while asphaltene aggregates themselves act as a relaxation agent due to their attached stable radicals.