  In Dyson-Schwinger studies of the Yang-Mills propagators the four-gluon
interaction has been usually neglected due to the related technical
difficulties with the associated two-loop terms and especially their
renormalization. A possible scenario to renormalize these fully-dressed
two-loop terms is presented. Preliminary results for the Landau gauge gluon
propagator are shown. Implications for the gluon propagators in maximally
Abelian gauge are discussed.
