Copper vs Aluminum crush washers

[scfoxtrot]

I changed my oil a couple of weeks ago using a new copper crush washer and torqueing drain plug to 50Nm as specified. It now drips ever so slightly. is there a difference in crushability between copper and aluminum? Is aluminum recommended by Porsche or is either metal acceptable?

[Reiver]

I've never had a leak/seep using the aluminum washer P recommends.

[Scnell Gelb]

Copper sealing washers would be appropriate for steel bolt+ steel sump
Aluminum for Al+Al. Look up "galvanic corrosion".
The thickness of the crush washer is important+ the obvious cleanliness,pitting and torque. Try a washer that is at least 1.5mm thick ?

[scfoxtrot]

Thanks for the advice, I'll get it swapped out this weekend.