what is the specific polyurethane item ??? I think of bushings (hard platic, kinda shiny) and probably would not coat with anything more than lubricant.
If its plastic and textured I would try a protectant like Black WOW in a small area first. If its painted plastic then I would stick to cleaner wax, or sealant for protection.
If its plastic and textured I would try a protectant like Black WOW in a small area first. If its painted plastic then I would stick to cleaner wax, or sealant for protection.