Oxidation performance of thermal barrier coatings (TBCs) deposited by the axial suspension plasma spraying (ASPS) method was evaluated under isothermal and cyclic conditions with a peak temperature of 1080 °C. The TBC systems are based on two nickel-based superalloy substrates (CMSX-4 and IN738LC), platinum aluminide bond coat (BC), and yttria-stabilized zirconia (8YSZ) top coat (TC) of either vertically cracked (VC) or columnar structure. Samples with IN738LC substrate exhibited longer isothermal oxidation lives whereas the ones with CMSX-4 substrate showed greater cyclic oxidation lives. Outward diffusion of W and Ta in TBC systems containing CMSX-4 was found to have progressed to the interface between thermally grown oxide (TGO) and TC; this has contributed to the reduced isothermal oxidation life. The longer cyclic oxidation lives of TBC systems with CMSX-4 were attributed to less coefficient and thermal expansion (CTE) mismatch between coating layers (reduced strain energy) and better creep resistance of diffusional BC on CMSX-4, hence less TGO rumpling. TBC systems with columnar YSZ had longer isothermal oxidation lives while those with VC YSZ seemed to result in longer cyclic lives.