The thermally grown oxide (TGO) formed on CMSX-4 coated with Pt-aluminide bond coat was studied by isotopic oxidation and photo-luminescence piezo-spectroscopy (PLPS). It was found that La doping in the CMSX-4 substrate suppressed inward oxygen diffusion along TGO grain boundaries which was the dominant TGO growth mechanism without La doping. The different oxidation mechanisms led to distinct TGO stress distributions and different crystallographic orientations of the α-Al2O3 in the TGO. In the sample without La doping, the residual stress was uniform and the α-Al2O3 crystallites were found to be preferentially orientated with their c-axis in perpendicular to the substrate surface, whereas in the sample with La doping, the residual stress distribution was found to be bi-modal with the existence of low stress zones, and the α-Al2O3 crystallites were preferentially orientated with the c-axis in parallel to the substrate surface. The TGO growth stress was estimated to be −0.6 GPa (compressive) for the sample without La doping and 0.2 GPa (tensile) for the La-doped sample. Low stress zones are speculated to correspond to local damage caused by the tensile growth stress at high temperature.