Why Are There Plastic Parts Inside Your Engine?!

Why are there plastic parts inside a hot metal engine?! ⚙️️🛢️
Inside most modern engines, a heavy metal timing chain spins at thousands of RPMs to keep the engine's valves perfectly synchronized with the pistons. Because this chain is constantly whipping around, it needs to be held tight so it doesn't violently slap against the inside of the aluminum engine block!
To solve this, engineers use heavy-duty nylon or plastic timing chain guides! A mechanic slides these durable plastic rails into the engine block next to the chain. Then, a mechanical tensioner wheel is bolted into place to push against the chain. The tough plastic allows the metal chain to glide smoothly over it without grinding metal-on-metal. Finally, the mechanic soaks everything in fresh engine oil so the chain doesn't burn up on its very first start!