Using these engine bay caps is easy. First, take the internal fitting from your original OEM caps. Gently apply pressure to pry them out, and then snap them into the new Billetworkz caps. Once you've done that, you can install the new caps on your 2015 - 2025 Subaru WRX. As for maintenance, since they're anodized, they're pretty durable. But it's a good idea to clean them regularly with a mild soap and water solution to keep them looking vibrant. Also, make sure the internal fittings are always in good condition and properly snapped in. If you notice any issues with the fit or if the caps seem loose, check the internal fittings right away.