Compounds of polytetrafluoroethylene (PTFE) are widely used in the automotive industry world-wide, especially in high performance dynamic seals, such as piston rings, transmission seal rings and radial crankshaft seals. Fillers are blended with virgin PTFE to selectively improve physical properties without compromising the unique lubrication behavior (the art of compounding). Dyneon LLC, a 3M Company, is the world's largest compounder of PTFE and also leads in the testing and design of state-of-the art compounds offering selected combinations of properties. PTFE is not processed like a “normal” thermoplastic, but in a fashion similar to ceramic or powdered metal. This paper outlines the technology to process PTFE, modified PTFE and their compounds and the types of fillers currently used. The physical property enhancements given by various fillers are illustrated graphically. Data include wear resistance (tribological data) and deformation-under-load at elevated temperature (extrusion resistance). Two illustrative examples of successful solutions to real-life automotive sealing problems are outlined.