Polytetrafluoroethylene (PTFE) can form tribofilms that help achieve a near ultralow wear rate (2×10 -6 mm 3/Nm) without requiring fillers, when the steel counterface is pre-oxidised and exposed to ambient moisture. This filler-free approach may enhance PTFE recyclability. This study explores the tribofilms’ structures and their robustness under various sliding conditions. The tribofilms, composed of brittle, compacted chelated iron carboxylate micro-agglomerates, endure at least 10,000 sliding cycles on smooth steel surfaces provided ambient moisture is continuously available. However, removing moisture at any point leads to irreversible film failure. On rougher surfaces, the films exhibit limited abrasion resistance. These tribofilms also appear to improve the PV performance of unfilled PTFE by at least 17 times, expanding its potential for demanding tribological applications.