I ride motorbikes through the winter and use acf50 which is great stuff, but recently I have been using some Honda Moly60 paste. It's expensive but probably any molybdunum paste would do. I am amazed at how it has remained on the rear sprocket, the brake pipe banjos and various other crappily painted mild steel brackets. The beauty of it is that it seems to stay a bluey grey colour and so far hasn't collected any crud - I don;t know how that is possible but it looks great. I am assuming that when I clean it off in the Spring the metal underneath should be pristine. Several washes with plain water hasn;t removed it, and I doubt soapy shampoo would either, but I have been careful not to brush those areas. I think WD40 will remove it when I want to. I still use acf50 on bolt heads etc
Mike