There was some discussion on a Samba forum about Bars Leaks, which made me think of this product that was recommended by mark Dearing of Salem (VA) Imports. I don't recall hearing much discussion of it here, so I thought I'd bring it up. 

Subaru had some of the same problems with one of its engines as the VW waterboxer, and apparently insisted that their customers have this little bottle of stuff installed before they could persue more expensive fixes under warranty.

It's called Cooling Syytem Conditioner, made by Holts, and is not thick and gummy like some other products. It is a red liquid. Maybe it is supposed to swell up the gaskets? Anyway, the back of the label, which I just accidentally looked under, as it doesn't look like you should pull it, contains the ingredients and health warnings.

It contains proprietary resin solution, Borax decahydrate, and Linseed meal.

Here's some discussion of it on some Subaru fourms:  

http://forums.nasioc.com/forums/archive/index.php/t-488157.html

http://www.talkaboutautos.com/group/alt.autos.subaru/messages/139339.html

I put in a few bottles- more than one because I figure our cooling systems in the Vanagon hold more than the Subaru- but the jury is still out as I had to drain some coolant for another reason and am still adding a little coolant to get it topped up just right.

Has anyone had experience with this product?

Ed