Since last Saturday (19 Jan 2008) I've received three virtually
identical questions about stem seals. I assume this reflects an
article in some magazine or a topic on some forum.
http://bobhooversblog.blogspot.com/2006/11/vw-valves-guides-and-seals.html
The blog article above contains a generic answer to all three
questions -- and probably to the Mystery Article which has created
this sudden interest.
-Bob Hoover