Here are a couple of cell phone pics....not good but you get the idea. I keep the gun in a leather holster in my truck almost 24/7....and I live in hot, humid south Georgia. So I guess I can blame myself/the weather....SO....how can I fix this myself? Steel wool and machine oil?
Looking at those pics, I'm thinking it's damper in the truck than you think.
If it were mine, steel wool to clean it off, then maybe a gunkote or similar surface treatment. Or replace with a stainless or nickel version.
"As was the man of dust, so also are those who are of the dust, and as is the man of heaven, so also are those who are of heaven. Just as we have borne the image of the man of dust, we shall also bear the image of the man of heaven. "