  The variational method employing the amplitude and width as collective
coordinates of the Klein-Gordon oscillon leads to a dynamical system with
unstable periodic orbits that blow up when perturbed. We propose a multiscale
variational approach free from the blow-up singularities. An essential feature
of the proposed trial function is the inclusion of the third collective
variable: a correction for the nonuniform phase growth. In addition to
determining the parameters of the oscillon, our approach detects the onset of
its instability.
