re:  http://www.aagaskets.com.au/gasketnews_coolantkill.htm

Thanks to Peter for referencing this article.  BTW, I think
"welsh plug" is called freeze plug in the USA.  Also, while
I'm not naive enough to believe all auto service
establishments in the US are honest, I do believe they would
have a hard time finding a manufacturer or supplier of
sub-standard coolant and hardly think they would think it
worth their effort.  What they're more likely to do is
install phospate-containing coolant in engines where it's
prohibited, and that's why VW owners should insist on blue
(euro spec) or orange (Dex-Cool).  And, yes, Dex-Cool will
let you know if something somewhere is not well sealed.