Asia’s refined product markets are being swamped by a wave of gasoline as a long-lasting crude oil glut spills into the one fuel market refiners had hoped would save them, ruining margins and dragging down share prices across the region. Singapore’s benchmark gasoline margins – long the bright spot for Asia’s oil processors amid rock-bottom profits earned on diesel, jet and shipping fuel – have more than halved since the beginning of 2016, when they were near at least a seven-year high for first-quarter values. With gasoline’s slump, overall refining margins in Singapore have dropped nearly 60 percent since the beginning of the year, buckling under the weight of the fuel products pumped out of oil plants as refiners feasted on crude prices that were as low as three-quarters of their mid-2014 levels. […]