Rotary Engine wrote:

Th local aluminum radiator supplier recommends the plastic tanks ( on his
website) before I contact him, what is the recommendation on the plastic
tanks - I heard they were prone to failure much more quickly than the full
aluminum ones. I'm sure the racing people use full aluminum, perhaps for
that reason.
George (down under)

Plastic tanks have been used since the 1970s.  They are reliable.  I
would never use one in an airplane, though, because the few ounces of
extra weight is a small price to pay for the significantly greater
strength of aluminum tanks.

Keith Wood

Most hard plastics in cars last about ten years here in Socal and then become
brittle and crack easily. I am no expert on plastics by anybodies wildest
imagination but I think it is a process called out gassing. If you can
smell it--- it is out gassing. Certain compounds are leaving the plastic
changing its mechanical properties.

Non metallic objects going into space are tested by cooking them in a
vacuum chamber. One example I know for sure is the Space Shuttle
tires. Black "rubber" hoses and is another material that
self destructs over time. According to Cummins engine manufacturer
silicone hose does not. That is also a reason why new cars have a smell.

I would never ever use plastic rad tanks. One crack could kill you.