Hello,

I feel kind of dumb for asking this, but i cant figure out what it is for. I have a 2005 A6 4.2 with a BNK Engine. Sometimes the oil filters I get come with the big o-ring, pretty easy where that one goes. However, there is also a metal washer in the box. It isnt the right size to be a drain plug crush washer, but I dont see a place for it. I dont remember ever taking one out; and some of the Hengst filters I have gotten come with a tiny one instead.

I've looked on diagrams, even the Bently service manual I have, but none of the diagrams are for the BNK engine for some reason. I attached a picture of it. 'Filter1' is some filters, just the large washer. 'Filter2' shows both washers. I have read the small washer is for a filter drain, I cant find it. Is that in the bottom of the oil pump?

Is it a oil plug washer for some other application? Or am i not putting it somewhere where it should go at the oil change? It appears to be the same size as the internal tube of the filter, but i wouldn't think it would go between the filter and the housing on the bottom, looks like that wouldn't seal very well.

Thanks in advance!