Core level photoemission experiments using synchrotron radiation were performed in order to study the properties of the SiO2/SiC interface on Si-terminated 4H-SiC surfaces after different oxygen exposures. The surfaces were oxidized gradually from 1 - 1.2x10(6) L at both room temperature (RT) and at 800degreesC. Recorded Si 2p and C Is spectra show only two oxidation states, Si+1 and Si+4, at both temperatures and no carbon containing by-product at the interface after the largest exposure investigated, 1.2x10(6) L. A clean and well ordered 3 surface is shown to be possible to re-create by in situ heating even after the largest oxygen exposures made at 800degreesC.