Plastic end-caps are cost reduction techniques, certainly NOT an improvement. Well my replacement plastic radiator failed. I thought it was from the core, but it was coming from the plastic hose barb inlet to radiator. Obvious thing is to tighten. No luck. Humm………I took it apart. Plastic is DEGRADING !!!. In particular the plastic has chipped pealed, and roughened. It has SOFTENED in a major way.Fluid leaking past. Plastic has consistency of hard cheese!!Unbelievable! Just JUNK. Have metal radiator on way, but car is dead and cannot move.What to do? I cleaned off pealing plastic hose barb, to loosen scale, then wiped with alcohol. Now apply a thin coating of silicone (RTV) to form new sealing surface. Let cure 24 hours. WHAM, leak gone. Will change radiator soon. But plastic end cap TREACHEROUS. Failure was hidden, but a lot of fluid loss.