The copper washer is for the drain plug on the crankcase.

Is it possible that there's something wrong that could inflict the same damage on your new filter? Are you tempted to check it before it is time to replace it?

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1996 C280 289K Traded
1997 E420 167K Traded
2001 S430 240K Traded
2010 E550 4matic 80K
2000 GMC Jimmy 198K Gone to Boneyard
2003 Camry LE 196K
2011 Mazda3 i Sport 31K