  We have renormalized a classical left-right model with a bidoublet, and left
and right triplets in the Higgs sector. We focus on oblique corrections and
show the interplay between the top quark, heavy neutrinos and Higgses
contribution to the muon $\Delta r$ parameter. In the SM, custodial symmetry
prevents large oblique corrections to appear. Although in LR models there is no
such symmetry to make vanish the quadratically diverging terms, we have shown,
that heavy Higgses contributions to $\Delta r$ are under control. Also the top
contribution to $\Delta r$, quite different from that in the SM, is discussed.
However, heavy neutrinos seem to give the most important contributions. From
oblique corrections, they can be as large as the SM top one. Moreover, vertex
and box diagrams give additional non-decoupling effects and only concrete
numerical estimates are able to answer whether the model is still
self-consistent.
