We report temperature-dependent behavior of the zero bias tunneling conductance (ZBTC), derived from tun neling spectroscopies on as-grown Bi2Sr2CaCu2O8+5 (Bi2212) single crystals taken with evaporated Zn and Pb planar junctions. At Tc the measured ZBTC shows a kink which gives an in situ measure of the superconducting transition temperature (Tc). Below Tc, the T2 dependence of the ZBTC has been observed repeatedly as a new evidence of the d-wave symmetry in Bi2212.