[fatoldfool]

Flashings (thin small flat strips or pieces) are not uncommon in cast aluminum assemblies like small motors, some are formed by mold separations and somewhere along the line someone is supposed to break or grind them off. How much or how many depends on the manufacturers quality control and how proud of his job the worker resposible felt that day. These aluminum flakes won't catch on a magnet. I am just throwing that out, and I don't think that is the original posters problem. I have done a bit of work on "classics" ( read junk that has been sitting for years) and an accumulation of silvery gunk is common in the bottom of oil pans and the depressions in cylinder heads of overhead valve engines. You should have seen the accumulation in a 1929 Buick engine that had done duty as a sawmill engine until about 1954, then sat until 2008. I have been told its a combination of broken down oil and acids. Whatever it is, it takes a really stiff brush and kerosene or diesel oil to clean it up. The reason I think the original posters problem is assembly lube, a lot of manufacturers use a product like Lubriplate (silvery thick paste) as assembly lube, and of course the break-in oil dissolves it and out it goes with the first oil change, looking very much like metalflake. Sorry for the long post...