I have a 1983 Honda and the aluminum shines like a mirror. It didn’t always. When I got it the metal looked dull and weather possible damaged. It is amazing what buffing it can do. From garbage to mirror finish. Very satisfying to watch aluminum being polished. The aluminum did loses some of the outer layer that had oxidizes but looks brand new once cleaned up. Looks new and has the structural integrity to be used in aircraft is not the same but for the purposes of a motorcycle cover it is just fine. There are many other applications for aluminum that structural integrity is not if concern like heat sinks. The LED light I am building uses aluminum extrusion as heat sink.