"We have invested Rs 1,330 crore to revamp our systems to make BS-IV complaint diesel and petrol from next year, refinery director Sanjiv Singh told PTI.
The 13.7 million metric tonne Gujarat Refinery was dedicated to the nation on October 18, 1966.
The refinery was started with capacity of 2 mmt per year and has since been ramped up to 13.7 mmt now and is gearing up for further expansion to take the capacity to 18 mmt at an investment of Rs 20,000 crore.
The expansion, which is expected to be completed by 2020, will make this facility the largest refinery for the nation's largest oil marketer.
The refinery has the distinction of having set up the country's first fluidized catalytic cracking unit (FCCU) in 1982 and the first hydrocracker plant in 1993.
It also has the country's first diesel hydro desulphurization unit (DHDS) which was set up to reduce sulphur content, in 1999 to meet BS-II quality.
In 2004, IOC set up the world's largest single train linear alkyl benzene (LAB) plant here, marking IndianOil's big-ticket entry into the petrochemicals field.
Today, IOC is the second largest player in the LAB market in the country and exports it to over 20 countries.