I am not sure if you have noticed this before (or anyone else for that matter), the City IDSi or even the Steermatic and IVTEC when filled with 3.7L exact...... donot show oil Level upto the top mark on dip stick.
Which is Perfectly Normal.
Why??? Becaue the the two marks on the dip stick show max and min level, and your oil level should be in between.
Just as low oil can have catastropihc results to an engine, similarly a higher oil level (than max specified on dipstick) can lead to other problems such as oil aeration, thus resulting in foaming by coming in contact with crack shaft. This will lead to struggle by the oil pump to pressurize the oil supply line and also cooling ability of oil will reduce, May lead to an overheated engine.
Anyways thats the story of not filling above max. On safe side, 3.7L as specified by manufacturer fills it near to the point you have marked on your dip stick.
About the change interval, i believe its 5000KM or 6 months (which ever comes first) as highlighted by @babarhyd
Reporting on duty....Sir!!!!! (only when its a City 03+)
By the way, as per City Fan Club, I would also suggests the OP to use Caltex Havoline 10w40
Well thats the first time I am hearing this. Uncle @capsat , you just need an excuse to blame Honda, dont you