somebody is doing his homework 
it's pourpoint. Not poor, like broke. 
Timing chains like good oils an frequent changes.
under normal european conditions a 5W30 is good enough for a micra, as longs as your not racing. And it helps a little bit with fuel consumption over "thicker" oils.
As for Specifications, i couldn't find a specific one for the old NIssans. The old Standard would be ACEA A3/B4 to go with. These are common and cheap to get either.
you could take the more modern A5/B5 too, if you want a more modern formula.