WS,
I also have Civic1995 with D16 ZC. Oil 10W30
45L Tank Capacity.
I mostly use regular fuel and always drive with the AC on, so it's giving me around 10kmpl at least within a city.
My daily commute is 50km. The RPM stays around 1.5 and I do quick gearshifts without letting the engine start missing or feeling heavy. At the 50km speed, the fifth gear is in place. Trust me it requires patience, yet I get 10. Since the engine is non-vtec, I think this the best one can get.