India will switch to the world's cleanest petrol and diesel from April 1, when it moves to Bharat Stage VI-compliant fuel from BS-IV grades. India will join the select league of nations using petrol and diesel containing just 10 parts per million of sulphur and emission standards are as good as CNG. All refineries began producing ultra-low sulphur BS-VI petrol and diesel by the end of 2019. Oil companies have now undertaken the tedious task of replacing every drop of fuel in the country with a new one.