The 40-year old refinery was unable to get sufficient yield of petrol and diesel from processing other types of crude.
The utility then tested about 600 different types of crude combinations, Minister Yapa said.
CPC has now found that 80 percent UAE Murban Crude and 20 percent Oman Blend gave a higher yield than even Iranian Light he said.Yapa denied that Sri Lanka has imported Iranian crude through third parties, though reports of such shipments have emerged from time to time.
He said Sri Lanka was unable to import Iranian crude from July 2012.
The old refinery turns out a high percentage of furnace oil and it lacks technology to crack longer molecules to diesel and petrol, generating higher volumes of furnace oil even with light crudes.
Minister Yapa said several proposals to upgrade the refinery are in the final stages of being evaluated.