i also own a i-dsi and oil level is decreased but not so much,may be coz i use very thin oil. i.e Liqui Moly 10w40. i used to use Zic A + and never once the level decreased.May be my car loves the taste of Liqui Moly
another thing that in manual it is written that oil level should be B/W min and max mark on dip stick but oil walas fill it to max mark! so what should we do?