The problem with some antiques is that the production specs of that era were of greater latitude than the precision machines of today produce.. No seals were used and many depended or grease or heavy oil to seal the crank case. (Many Row Boat Motors have grease cups on the crankshaft bearings) Todays oils are fantastic as far as eliminating ware but some antiques may require a shot of heavy weight oil to properly seal the motor. Unfortunately this promotes carbon formation, requiring periodic service to remove. If ignored, carbon flaking off the combustion chamber con score cylinder walls. At none time this was thought to be caused by a lack of lubrication which made them recommend more oil . . . 😆
