Here are before and after pics of our '97 Cutlass with 197k miles on it. Mind you, I do this at least once a year, so this is merely contaminants that have built up since last spring. I think the pics speak for themselves.
Passenger Rear Door
The rust seen here has "bled" through from the inside door seam. Before:
After:
Before:
After:
Here it is, all finished, with fresh wax. You can probably guess the year, but can you guess how many miles are on it?
