I guess with a really crap oil you could run into issues but in my experience the oil carried in the fuel mixture remains on bearings and cylinder walls long after the fuel has been burned.
On the weekend I rebuilt my sons Motocross Bike (KTM85) and had to freeze all the new gearbox and main bearings while heating the 2 halves of the crankcase to 180 degrees c in the admirals flash Bosch oven (she was away at the Barrier on a girl's trip 😉)
I always run the bikes out of fuel before loading them in the trailer at the end of a ride.
Even though I thoroughly degreased the cases, th