Obviously not having one, I cannot fully answer.

However, air cooled engines often run a bit hotter than water cooled ones*. My understanding is S&S recommend a Mobil 1 oil, and when I last looked into oils, Mobil 1 could be subjected to higher temperatures than anything else without going out of grade.

* Piston manufacturers often recommend greater clearances for air cooled engines for that reason.


1930 Super Sports Aero 'The Elk'