Hey guys. So I use a well known gun oil that can settle out, ever so slightly, but it does. A good shake and its back in suspension. One of my clear,4oz bottles, I could see a little build up on the bottom that wouldn't mix in. So a couple years ago , I dropped a platted 1/4 nut in the bottle to help agitate it. So this morning , I noticed that nut appeared pretty dark, as it was easy to see in the bottom of the bottle. I pulled the nut out, and at first glance I thought it was rusty. Completely brown. Like the patina on a 100 year old gun barrel. Not crusty, but has a egg shell like feel to it. So, what is it? I can't imagine it could rust being totally covered in oil. Is it reaction of some kind? It doesn't come of easily at all. Almost like its etched into the metal. Any thoughts? I took a couple pics , but you really can't tell much by them.