Also I would add that using a Dremmel with a polishing head and Autosol will help to get a shine on an aluminium filler cap
Certainly easier to get a shine than doing it my hand
Personally I like a hand job.
I rather like polishing the filler cap, Autosol or Silvo and then a final coat of Megs Alloy cleaner with wax. I've even been known to clean the factory's hire car caps!
