S-Oil returned to profit in the first quarter as a jump in crude prices triggered by the Middle East conflict delivered hefty inventory gains, more than offsetting headwinds from scheduled maintenance and a domestic petroleum price cap. According to regulatory filings released Monday, the Aramco-controlled refiner posted a consolidated operating profit of 1.23 trillion won ($835.7 million) for the January to March period, swinging from an operating loss of 21.5