I just read that some of the Subaru guys are using NPG+ coolant.
   http://www.evanscooling.com/main31.htm

I just had a chat with Dave at Evans. It sounds like this stuff might be
helpful, plus these guys also make reasonably priced custom radiators. Dave
was very knowledgable concerning the problems of cooling an "off-road"
vehicle, especially when it's a pusher :)

Anyone using or know anything more about this stuff?
John Slade