Energy values for different states of oscillators with quartic, sextic and mixed quartic and sextic anharmonicities have been calculated employing the renormalized hypervirial perturbation series. The K parameter, which yields the best convergent series, has been found to be different from the one derived from the analytic approach put forward by Chaudhuri and Mondal. The accuracy of the values obtained and the dependence of K on the perturbation parameters and the quantum numbers of the state have been discussed for all the cases.