Are you sure you are using the Honda Engine Oil for 3 years and also how can it be recommended for all Year with 0w-30 Viscosity as i think 5w-40 or 10w-40 or 5,10,25,20w-50 should be used here in Pakistan Cars.
How about the car feeling on the Liqui Moly, while your Mileage definitely make difference with Viscosity but it cant for 6 kmpl as if your drive on same course and have 6kmpl difference it can be issue as i saw 10 kmpl difference on change of terrain.
As for mileage many things matters like Wheels, Wheel's Pressure, Driving Style, Terrain, Load, AC Use, Fuel quality like PSO even thr Hi-Octane sucks. Liqui Moly in any ground is better engine Oil thn Honda Genuine Engine Oil.