Hughes,
Many OEM's "market" lubricants under their brand name. It possibly started with the Japanese who started marketing "Genuine oils."
Principally it is a good idea as the OEM seek to protect their equipment from damage and subsequently warranty /guarantee claims by the use of wrong lubricants.
Reputed manufacturers rarely take short cuts and it is in all probablity that these OEM's will choose a top of the line lube manufacturer. The only problem is that some of the top brands like "Castrol" may; or may not supply oils, if it does not carry the (Castrol) brand name. Thus we now have joint branded products like Castrol-Hitachi Excavator fluid (Castrol Hyspin TH 46).
The option then, for OEM's, is to chose from lesser brands (Valvoline, Pennzoil etc) if OEM wishes to camouflage the "manufacturer" of the lubricant.
Thus the use of Atlas Copco Roto-H Compressor oil provides an in-built warranty & guarantee. The only difficulty is that such "Genuine oils" carry thier own mark up in price and do not come cheap.
If you are persistent you can "discover" the "manufacturer" of the oil, but in all probability it may not be Shell. Further, the OEM may have obtained "undertaking" from the Lube manufacturer not to sell the same oil in the market, "with the same name."
Hussam Adeni