Do I need the Mini radio antenna at all? I use the factory Navigation and SiriusXm but never listen to AM or FM radio - does the factory antenna play any role in satellite or gps reception? If not, I might unthread it and try to find some kind of finisher cap to protect the metal base threads. Thanks.

 

I was driving a lot with antenna removed on R56 as I mainly used CarPlay and radio antenna was interfering with roof box. No issues with corrosion and even radio signal pickup was decent. I didn't have a factory navigation in my car, but I would be surprised if radio antenna has anything to do with either nav or SiriusXm - they usually have their own antennas. You might also look into aftermarket shark fin antenna as an alternative.