I think the steel pipes last long enough that it isn't worth putting in
anything else.  The steel pipes under my 20-year-old Vanagon only have
rust where they're clamped near the front.  I'm hoping if I touch that up
with some POR15 it'll keep it from going through.  Even if I eventually
have to replace them, I'd expect the replacements to last until the rest
of the van has turned into dust.

It might seem counter-intuitive, but steel tends to last a long time in
cooling system applications.  The chemistry of protecting it is pretty
well understood and it's not as reactive as aluminum or solder.

             _ _
  __ _ _   _| | |  | David M. Brodbeck (N8SRE)              Ypsilanti, MI
 / _` | | | | | |  +-----------------------------------------------------
| (_| | |_| | | | @ cyberspace.org
 \__, |\__,_|_|_| "The VW camper is a brilliant invention -- it's like a
 |___/             Swiss army knife for the road... It's the stealth RV."
                                                        -- Wayne Curtis