Anything that will keep the oxygen off will keep the shine on, but most of the things that are available simply don't work well. For some parts, like sprocket covers or alternator covers, you can probably have a clear powdercoat put on after you polish them, but like any other coating its going to have problems bonding to a well polished (and cleaned) surface. Almost no paint will work satisfactorly; there is no opportunity for a chemical bond (how most clear coats work) and because the surface is so highly polished there is also no "tooth", as the painters say, for a mechanical grip. Think about it this way, when you prep a surface for paint you normally don't sand to any finer than about 400p grit because the paint needs those microscopic scratches to help it adhere. When you polish an aluminum cover you will be doing something that is roughly akin to sanding with about 8,000~10,000 grit, or so; not much for the clear to adhere to.
As for the wipe-on stuff, the only guess I have about it is that its some sort of wax, which will certainly work for a little while - but only for a little while. And then of course if you use it and then want to try some other coating you'll have the pleasure of having to completely remove the old wax, usually a task that requires considerable effort.
