Chrome rings and bronze bushings don't have anything to do with what oil you burn in an engine. The reason they recommended regular oil back then is simple: 2 stroke oil didn't exist.
You CAN use regular 30 wt oil in it, but there's no reason to unless you like SMOKE and cleaning out your exhaust ports once a month...
You CAN use regular 30 wt oil in it, but there's no reason to unless you like SMOKE and cleaning out your exhaust ports once a month...