From the Spec Sheet:

Maximum Working Pressure:
   160psi (11 bar) @ 73.4�F (23�C)
   100psi (6.9 bar) @ 180�F (80�C)
   80psi (5.5 bar) @ 200�F (93�C)

So following that on down to the working pressure 
of  the vanagon cooling system, it would be 
pretty dag-on hot.  Some quick lookup of PEX in 
general said it could go up to 150 degrees 
C!  Would need of course to get more info on this 
particular material.  I also could find no info 
on tolerance to coolant, but I gave up pretty 
soon.  When I was playing with my CPVC heater 
shut off valve, my internet research said that 
CPVC was not tolerant of automotive coolants.  I 
had mine in service for almost a year though, and 
it seemed fine when I took it out.

Edward

At 06:50 PM 6/17/2012, Dave Mcneely wrote:
>Is that 200 C or 200 F?  Probably the latter, 
>which is marginal for the application 
>contemplated.  I would expect failure due to 
>heat, even if the engine never "overheated."  But what do I know?  mcneely
>
>---- Ken Lewis <kdlewis@NORTHSTATE.NET> wrote:
> > Would this work :
> >
> > http://www.watts.com/pages/_products_details.asp?pid=6761
> >
> >
> > Two hundred degree maximum operating.
> >
> > One might be able to eliminate a few rubber hoses by clamping directly to
> > distribution nipples.
> >
> > Ken
>
>--
>David McNeely