A study of the (18O,16O) two-neutron transfer reaction at 84 MeV incident energy was pursued at the Catania INFN-LNS laboratory on several targets. In the energy spectra obtained from the light targets, several known low lying and resonant states of the product nuclei are observed. Instead, the spectra from the heavier targets are dominated by the appearance of a broad bump, indicating that more dissipative processes are contributing. In this case, calculations based on semi-classical transport theories seem to indicate the possible occurrence of dissipative reaction mechanisms.