[Efthreeoh]

I'll chime in. Just to put some creds out, I have a technical degree in manufacturing engineering (I no longer practice in manufacturing) and I've taken two courses in college on "plastics", I'm an old codger now with experience owning and working on cars from the early 1970's to 2022, and I keep my cars a long time and to high mileages. My oldest car at the moment is 27 years old, newest is 18 months. Over my lifetime I've seen the infusion of plastic parts in the engine compartment and other areas of the automobile. I'm all for it.

As many know, my 2006 E90 has racked up 400,000+ miles. Well documented here on E90 Post, it's really not had a lot of issues related to plastic engine parts. Modern cars with plastics in them last far longer and require far less maintenance than cars from 50 years ago (1970's); 400,000 miles on any car is impressive and indication of just how well-made modern cars are. Plastics are used heavily in cooling systems now because they work better. They work better because of chemistry. Antique cars with cast iron engine blocks, aluminum heads, and copper/brass radiators required extensive cooling system maintenance because there was a lot of cooling system corrosion due to the mixture of the various metals. Modern cars with aluminum core radiators and plastic end tanks last decades and multiple hundreds of thousands of miles. And the maintenance schedule is drain the coolant every 100,000. A 1970s car, if you didn't flush the cooling system every two years, the radiator core would eventually spring a leak, or a pin hole would form in an aluminum casting somewhere.

Metals corrode in cooling systems because of electrical eddy currents that run through the engine metals and water-based coolant. Using plastics greatly reduces corrosion.