  The synthesis of superheavy elements stimulates the effort to study the
peculiarities of the complete fusion with massive nuclei and to improve
theoretical models in order to extract knowledge about reaction mechanism in
heavy ion collisions at low energies. We compare the theoretical results of the
compound nucleus (CN) formation and evaporation residue (ER) cross sections
obtained for the $^{48}$Ca+$^{248}$Cm and $^{58}$Fe+$^{232}$Th reactions
leading to the formation of the isotopes A=296 and A=290, respectively, of the
new superheavy element Lv (Z=116). The ER cross sections, which can be measured
directly, are determined by the complete fusion and survival probabilities of
the heated and rotating compound nucleus. That probabilities can not be
measured unambiguously but the knowledge about them is important to study the
formation mechanism of the observed products. For this aim, the
$^{48}$Ca+$^{249}$Cf and $^{64}$Ni+$^{232}$Th reactions have been considered
too. The use of the mass values of superheavy nuclei calculated in the
framework of the macroscopic-microscopic model by Warsaw group leads to smaller
ER cross section for all of the reactions (excluding the $^{64}$Ni+$^{232}$Th
reaction) in comparison with the case of using the masses calculated by Peter
M\"oller {\it et al}.
