It appears to be the thin Aluminum that is in the 4 foot side door paint has deteriorated, it is a very thin skin. I believe it is electro painted. In fact the streaks are a very light green.
The white smooth siding on the rest of the trailer is thicker and not an issue. I did not use Simple Green on the rest of the trailer. Tried a wax cleaner today on the door, no help.
Will try Magic Eraser and a light compound as suggested. Just want to get the green tint on the streaks removed, then use Dep floor wax as I have on the coach, it looks terrific.
If I fail I will paint the door to make it look correct.