Factory motors used to run as tight as his and straight 30 was what most everything came with back then and they weren't grabbing bearings, even in extremely cold temps.
I don't know what caused his issue, but I highly doubt it was the viscosity of the oil, the lack of full groove bearings, or similar.
Not that I know anything but this is what I was thinking reading through this thread, I'd reject the idea that it was too tight, too thick oil, etc. I'd think it was too out of round, was starved for oil, or simply didn't have .002 clearance...
I wouldn't want a 50 weight in an engine with .002 clearance, but people put 50 weight in tight engines all the time. Or engines that they have no idea what the clearances are, factory stuff, etc. I've put 50 weight in old worn out oil burners, who knows what the clearances were, but I wound them up tight and it was never an issue. Maybe they were just loose. But if 50 weight with .002 clearance was an issue that was going to grenade a lot of engines we'd be hearing about it a lot more often...
