  We studied kink-antikink collisions in (1+1)-dimensional spacetime for all
$Z_2$ symmetric $\phi^8$ models with four degenerate minima. Such a polynomial
model has only one free parameter, allowing us to conduct an exhaustive
analysis. We performed detailed simulations in all three sectors of the model.
We observed resonance windows from both localized and delocalized modes, as
well as a sector change with the formation of additional kink-antikink pairs.
Furthermore, we were able to show how collisions are modified when two
quadratic minima merge into a quartic one, causing the kinks to acquire a
long-range character. We demonstrated that when the tail not facing the
opposing kink is long-range, incoming kinks and antikinks decay directly into
radiation, as suggested in \cite{campos2021interaction}, by forming a large
number of small kink-antikink pairs. Finally, we briefly discussed whether our
analysis could be generalized to other polynomial models.
