The effects of vibrational excitation and translational energy, connected to mode selectivity and Polanyi's rules, are important issues in dynamics studies. To analyze these effects on the O(P-3) + CD4 reaction, an exhaustive dynamics study was performed using quasi-classical trajectory calculations on a full-dimensional analytical potential energy surface. The independent excitation of the C D symmetric or asymmetric stretch modes leads to reactions with similar reaction cross sections and product scattering distributions, mode selectivity being discarded. Finally, translational energy raises the reactivity more effectively than an equal amount of energy in vibration, thus indicating that for this "central barrier" reaction it is not clear how to apply the venerable Polanyi's rules. The strong coupling between vibrational modes is responsible for this behavior, which seems to be the general tendency in polyatomic systems.