A model solution system of 1,4-polybutadiene in oligomeric butadiene of high vinyl content is studied to show how polymer friction dynamics depend explicitly on the solvent dynamics and are approximately determined by the overall glass transition temperatures of the solutions as a function of concentration (i.e., weight fraction phi) and temperature T. Among the most striking findings are the invariance of the overall molecular relaxation time with phi from phi = 1.0 to 0.3 at a special temperature To Below To, the solutions possess longer reptation times than that of the pure PBD melt. Moreover, through oscillatory shear measurements of linear viscoelasticity, the scaling of the tube dilation with phi is found rheologically as a proportional to phi(-2/3), which agrees with the previous neutron spin echo studies. Since viscoelastic properties of the entangled solutions reveal dynamics associated with the polymeric component, a general methodology is established here based on the present model system for characterization of component dynamics in miscible polymer blends.