I can't seem to find the 30w Kohler oil around me and the only Cub Cadet dealer doesn't have either.
I have run Rotella 15w40 with no issues.
Here is a good oil with a high zink content that the local Hustler dealer sells around me. This is what I was running in my Onan's. Amazon is too expensive.
https://www.amazon.com/Kawasaki-9996.../dp/B00HVTF7YM