Reliance, which has a diversified crude slate and shifts purchases to maximise revenue, bought about 1.20 million barrels per day (bpd) of oil in August, a decline of about 12.4 percent from July, the data showed.
Reliance's two advanced refineries in western Gujarat state can together process 1.4 million bpd of oil, about a third of India's overall capacity. The complexity of these plants allows the refiner to diversify its crude slate continuously by testing new grades, and to improve refining margins.
In the first eight months of 2014, the private refiner shipped in about 1.24 million bpd of oil, an increase of about 1 percent from a year ago, the data showed.
In January-August 2014, Reliance bought around 43.3 percent of its oil needs from Latin America compared to nearly 45.1 percent last year, with Venezuela maintaining its position as the top crude supplier, followed by Saudi Arabia.
Qatar was the third biggest oil supplier to Reliance, replacing the Neutral Zone, a border area whose production belongs to Saudi Arabia and Kuwait.
The share of middle eastern crudes in Reliance's overall oil imports in the first eight months declined to 41.1 percent from about 44.3 a year earlier, while that of African grades jumped to nearly 13.4 percent from about 9.6 percent a year earlier.