The wife just bought a new Shadow, I asked the dealer to check the rear diff, he said we never check them.
Thats done at the factory. I told him about the numerous complaints about low levels and he said he had never heard anything of the sort.
I took the bike straight home, and checked it. Sure enough 2 ounces low....... In talking about the F6B ( he is a major Goldwing dealer) he also recommended a service between 600 and 1000 miles in which he also changes the diff oil. He said " it's cheap and easy to do so why not?"