I know this has been discussed ad nauseam so I figuered I will get it straight from VAG.
I know it has been said before, but here is my e-mail.
ORIGINAL
Motorenoele nach VW 503 01 erfuellen alle Anforderungen der VW 502 00,
zusaetzlich jedoch weitere Anforderungen fuer hochbelastete Ottomotoren. Damit
sind sie fuer bestimmte Ottomotoren auch fuer verlaengerte Wechselintervalle
zugelassen.
^TRANSLATION:
Motor oils with 503 01 certifications meet all the requirements of 502 00, and additionally meet requirements for "high load" (this is a direct translation, it is close to high demand/ high power I would say) gasoline engines. Therefor, they are cetified for gasoline engines with longer drain/ change intervals.
ORIGINAL:
Die Motorenoele nach VW 502 00 sind grundsaetzlich nicht fuer verlaengerte
Wechselintervalle zugelassen. Motorenoele nach VW 503 01 sind in der Regel
auch fuer alle Anwendungen zugelassen, wo VW 502 00 verlangt wird.
TRANSLATION:
The oils with 502 00 are normally not allowed/ intended for long drain/ change intervals. Oils with 503 01 are accordingly allowed in all applictions where 502 00 is needed.