S-Oils fourth quarter operating income of 65 billion won was a 30 percent improvement from the fourth quarter of 2013. Its quarterly sales revenue was 440 billion won, down 6.5 percent from the year-earlier period.

In its financial report released last week, the company said that it attributes the increase in income despite a decline in base oil prices to improved margins, which resulted from a sharp drop in feedstock costs.

S-Oil expects the growth to continue in 2015. Intensified market competition is expected due to new capacity additions, but the margin will be firmly supported by stable demand for high-quality lubricants from the United States and Europe and demand growth in Asia and South America.