The fluid changes should be every 25k to 30k for pan only changes, and for fluid exhange method you can go a little higher..

The aluminum is from wearing out of the planetary drum from the clutches banging around. It is normal to see that...What is the danger is the three dimension copper parts. Here is where the aluminum comes from.. See the first photo from post 13. The copper can come from the copper washer on each side of the planet gear in the same photo(you can see it)..

What do you guys think about this ATF filter? - Mercedes-Benz Forum

Martin