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Aims. A long timeline kinematic study of the archetypal CSO OQ 208 shedslight on the physical properties of the most compact radio sources.  Methods. Archival data from the VLBA at 15 GHz over a time span of 13.6 yrare used to investigate the kinematics of the radio source. The flux densitymonitoring data obtained at the Michigan 26-meter radio telescope are also usedas supplementary information.  Results. At 8.4 and 15 GHz, the two lobes are resolved into twosub-components, identified as hotspots. A knotty jet is linked with the NEhotspot and traces back toward the geometric center. The core is too weak to bedetected. Significant flux density variation is found in the primary hotspotswith the maximum level of 62% (NE1) and 19% (SW1). The peak in the flux densityof NE1 leads that of SW1 by approximately 5.00 yr, suggesting that thenortheast lobe is advancing and the southwest lobe is receding. This lighttravel difference indicates a radial distance difference between the twohotspots of 1.53 pc, which indicates an inclination angle of about 80.8 degreebetween the radio jet and the line of sight. The angular separation ratebetween NE1 and SW1 is 0.027 mas/yr (or 0.133 c). The inner jet knot moves at0.047 mas/yr (or 0.230 c), about 3.5 times the hotspot advancing speed.  Conclusions. The large viewing angle and the modest jet speed suggest amildly relativistic jet. The jet axis is close to the plane of the sky. Theseparation rate and the distance between the two primary hotspots result in akinematic age of 255$\pm$17 yr, confirming that OQ 208 is indeed a young radiosource. In addition to the hotspot advancing motions, sideways motions provideevidence that the lobes are obstructed by the external interstellar medium.

Kinematics of the Compact Symmetric Object OQ 208 revisited