I’m consistent with Randy’s advice these days. I also have a 10+ year old Kanoyama 80000 that I bought used and I’ve never put anything on it. It’s polished like a mirror and as supple as the day that I got it. Iwasaki says to never put oil on a shell strop, it will cut the polishing power in half.

Sometimes I do use neatsfoot oil, on desiccated non-shell vintage strops (rare for me these days), and on boar strops. I use it like Randy does, I rub it on my hands then rub my hands on the desiccated vintage strop or the boar strop. Then wait a few days and assess the results.