  In the Israel-Stewart's theory of dissipative hydrodynamics, we study the
scaling properties elliptic flow in Au+Au collisions. Initial energy density of
the fluid was fixed to reproduce STAR data on $\phi$ meson multiplicity in 0-5%
Au+Au collisions, such that irrespective of fluid viscosity, entropy at the
freeze-out is similar in ideal or in viscous evolution. Initial eccentricity or
constituent quark number scaling is only approximate in ideal or minimally
viscous ($\eta/s=1/4\pi$) fluid. Eccentricity scaling become nearly exact in
more viscous fluid ($\eta/s \geq$0.12). However, in more viscous fluid,
constituent quark number scaled elliptic flow for mesons and baryons split into
separate scaling functions. Simulated flows also do not exhibit 'universal
scaling' i.e. elliptic flow scaled by the constituent quark number and charged
particles $v_2$ is not a single function of transverse kinetic energy scaled by
the quark number. From a study of violation of universal scaling, we obtain an
estimate of QGP viscosity, $\eta/s=0.12 \pm 0.03$.
