Excalibur’s new SMF (synthetic mainframe) is GLASS FILLED NYLON not PLASTIC. Glass filled nylon is a super high strength, durable, heat and impact resistant composite used in high grade applications such as military weapons, assault rifles, handguns, aircraft components, automotive engine components etc, the list goes on. Handgun and assault rifle manufacturers such as HK, Ruger, Glock, and Sprinfield Armory use glass filled nylon frames. These are guns that you can bury in raw soil for 3 years, dig them up and fire them flawlessly. Excalibur knows EXACTLY what they are doing by using this material on their crossbows because it is high grade. You can find out more about glass filled nylon on Wikipedia, or just about anywhere on the Internet. Better yet, go to Bing.com hit images and type in glass filled nylon and see for your self the vast array of weapons and components are made by this material. As for the question of heat resistance, and can you put WD-40 on it, the answer is yes. This material has a melting point over 1000 degrees and is used to make intake manifolds on automobiles so you can’t hurt this material. It won’t bend, flex, chip, warp, melt, or dent.