Am changing the oil filter in my 2000 C230 Kompressor. I've noticed that there is a brass washer and a large rubber O ring. I installed the O ring, but can not seem to find a place for the brass washer; nor did I see one when I removed the old filter. Perhaps this model does not use the washer???

Thanks

 

perhaps it is for the oil drain plug

 

The brass washer should go on the oil pan drain plug. There should have been one there. It is a crush washer and has to be replaced at each oil change.