I work in the plastics industry and would only use the clear polycarbonate rocker covers for demonstration only. While polycarbonate is quite tough it is not resistent to petrochemicals. The covers will eventually yellow and crack at the attachment points. Ultem would be more resistent and would be able to handle the heat and chemical attack better but is a light beer bottle brown and much more expensive. Acrylic is more resistent to petrochemicals than polycarbonate but starts out at a much lower tensile strength (more brittle). All polymers used under the hood by the auto makers are resistent to oils, grease and temperature. These materials are typically PBT, Nylon, polypropylene, and other various blends and thermosets as well as specially treated rubbers and silicones.
Also, do not use thread locking compounds around or near polycarbonate when securing it to something with screws. They will craze and crack the material in a matter of minutes. Keep PC away from most cleaning solvents. Polycarbonate even has trouble standing up to repeated washing in a dishwasher especially with liquid detergents. It will eventually craze with microcracks and cloud up. This happens to clear food processor housing, clear blender housing, etc. These items will last much longer if washed by hand. my/ubbthreads/images/graemlins/twocents.gif
