I think you have 1KR-FE engine installed in your car.
Go with 5W-30 grade oil. I think Shell helix ultra 5W-30 (full synthetic) is the oil u should be using if u like Shell Brand. Please confirm from the oil can once purchased.
Viscosity is the resistance to flow of oil. It is proportional to the temperature. The bigger the number, the thicker the oil. An oil with less viscosity number will flow easily than an oil with high viscosity at a given temperature. The yellow Daba oil you have put is I think either 10w40 or 20W50 due o which your fuel consumption has increased.
You may change the oil to 5W-30 but also oil filter has to be changed.