What is the black material our radiator tanks are made from? Specifically later model, 1990 I'm really interested in. It almost looks like fiberglass or some sort of plastic mixed with another material. A quick google search comes up with "Because of the harsh operating conditions, the radiator tanks are made from glass-reinforced nylon, a plastic that features a high-softening point. The high-softening-point nylon plastic is what helps the plastic radiator tank withstand the pressure and temperatures involved."

Is this what we have?

 

Plastic. You could do an AVE test and try cutting or scraping to check for glass fiber reinforcement, but why? Plastic degrades with age. The tanks crack. Once upon a time you could get replacement tanks and rubbers and have a well equipped radiator shop replace the tanks. Then someone discovered it was easier, faster, and less expensive to just replace the entire radiator as a unit. One part to inventory, no fancy equipment, etc and so on. If the rad is fine, it's fine, if it's not fine, replace it, it'll be fine.

 

Radiator is fine, just want to know what it is made from. I'm curious like that.