A complete experimental study on the production and transport of long lifetime excited states has been done for Ar18+ on solid C targets, at a velocity of 23 a.u. and for a range of thickness allowing to vary the transport conditions from single collision to equilibrium (3.5 to 201 µg/cm2). A systematic determination of Ar17+ Rydberg l and 2s state populations has been performed using X-ray spectroscopy technique. Results are compared with predictions of different transport simulations (either developed on a quantum or classical phase space), which take into account multiple collisions and the strong polarization induced by the incoming ion (the wake field). Using Continuum Distorted Wave approximation for modeling the initial capture process, very good agreement is found between experimental Rydberg state populations and theoretical approaches limited to the effect of multiple collisions. On the contrary, the transport of the metastable 2s exhibits strong sensitivity to Stark mixing induced by the wake field. Limitation of each theoretical approach is discussed with respect to the different experimental observables.