When I was at the mower shop last the serviceman was replacing a Kohler short block.
He said the owner while not using it much decided on using a conventional 10W-30 oil.
The bearings mostly were shot with some cylinder scoring.

I don't understand how a conventional 10-30, regardless of the usage factor, would cause ruined bearings/scored cylinders. Something else must have been involved. A Kohler should last forever with any 10-30 out there, I'd think....