Dr. A8

OK, tell your spark plugs that the ones made by NGK with the Audi logo are no different from the ones sharing the exact same part number made on the same assembly line in the same plant and sold without the Audi logo.

FrenchToast

True for some parts, but not all. Can't speak for the ones in question, but, historically, coils fall into the latter category.

An article from a vendor is going to have bias.

There are many parts where the OE and OEM parts are built to different specification. They may be built in the same facility, yes.

The manufacturer owns the rights to the OE production process, which can include tooling, material certification, quality control, etc. The OEM can work around that contract and produce a part without the manufacturer logo, but it can't use any of the manufacturer-owned production process. Difference in quality depends on the part.

Dr. A8

I'm open to learning but you'll need to supply some kind of source other than "just trust me bro".

bg_2007Q7

Oh really, that's why the ngk non logo went out in two weeks. I've had the Audi logo plugs for over ten thousand miles now. You are incorrect brother, not everything is as it seems. It's your car, your money, your choice...

FrenchToast

My sources are anecdotal. That in itself is understandably cause for doubt, but I've heard enough anecdotes from people in the industry to believe it.

I'm not sure there will be a primary source anywhere that truly compares OE vs. OEM. The auto manufacturer contract usually prevents disclosure of their production process, and it isn't in the interest of the parts manufacturer to publish something suggesting their parts differ from the OE parts. Anyone who knows has signed an NDA, and by the time the contract expires they've probably forgotten about it.

From the top of my head, one example I've read is Dansk makes the stampings for various vintage Porsche-branded body panels. Dansk also has their own line of the same panels. The Porsche-branded parts are stamped on Porsche-owned tooling, while the Dansk parts are stamped on Dansk tooling. To further complicate it, neither fit as well as an original stamping.

As for coils, I'm told there are indeed differing quality control and internal performance criteria for different brands of a similar coil. Probably not all of them.

Don't get me wrong, choosing the OEM is usually the next best to OE parts. And in the case of a ten year old car, the OEM and OE parts can sometimes be equivalent as various contracts have expired. Again, it depends on the part.

On the other hand, that's not to say OE parts aren't value engineered: some more aggressively than others.

I typically suggest people research proportional to the criticality of the part.

-Wes-

This discussion is an excellent reason why the suggested retailer, FCP Euro, is the clear choice! They have a lifetime warranty on their products (perhaps not all, I don't know, but certainly on the non-consumables). If you go non-branded and the part lets you down, at least you don't just have to eat the cost.