I've also heard that techron was the only injector cleaner that did anything
for years.  I have used it occasionally on my several VWs over the years.  I
once even got the MSDS for it to see what was in it.  I remember Naptha
being one thing.  I also note the advice and this is what I usually do, to
put it in the tank when I'm going on a trip and will use the whole tank
pretty quickly, and then change the oil.  Apparently it gets past the rings
into the engine oil.

All of that may be complete balony.  I am also interested in any scientific
studies on the subject if they are found out there.

Edward