Want to be confused further?
I pulled the filter listed in the book for my 83 300D off the shelf the other day at autozone to show a friend the uncommon canister type as he'd never seen one. Now, it was either Fram(which I have a storie involving years of use and cutting them up to observe things is anyone wants to hear it) or it was there STP brand, which is made by Champion Lab's, as are MANY odd and end brand filters, including I *think* Bosche(before autozone quit carying them, there suposidly the same filter in the stp box without the black paint).
Anyway, this filter I pulled out and showed to him, you know what was stamped on it, clear as a sunny day?
Made In Germany
Right on top.
I've seen this before(long time VW driver). Sometimes at a chain like autozone, that HAS to stock filters from one manufacturer, if said manufacturer happens to not make a filter they want to stock, because it's not popular enough perhaps, they'll source the filter from somewhere else, label and/or paint it and stick it in there box.
This is just a theory born of several million miles of observation and oil changes mind you.
I know almost for sure Champion Lab's was makeing the Bosche filters AZ sold for a good while, and I'm almost positive the STP they sell now is still a Champion Lab's filter. Draw whatever conclusion you like. I just thought the Made In Germany stamp was interisting.
For the record I've had good service from filters made by CL, reguardless of who's name happens to be on them. However if I could buy Mann of Mahle or the other that was listed(I know those two from VW) localy, I would do so. And I may yet start ordering in bulk after some experimenting.
Knowledge is power, take it for what you will.
edit: Another note I usually make in this discusion, which ties to the above in a way. A given filter will often be of varying design/quality across a group of seperate applications. As in, filter A may be well made and fine and dandy for this Ford, but may well not be well made and fine and dandy for this Chevy.
I've seen first hand evidence of this several times. I've also seen manufacturers quietly change construction techniques without a word, often not to the better. It pay's to be observant.