(Oil & Gas 360) – U.S. Gulf Coast refiners are benefiting from sharply higher global tanker rates as shipping disruptions associated with the Iran conflict widen discounts on Canadian and Venezuelan heavy crude, providing a competitive advantage over Asian refiners facing significantly higher transportation costs.The shift in global petroleum trade has strengthened refining margins and contributed to robust third-quarter earnings for major U.S. operators, including Valero Energy, Phillips 66 and Marathon Petroleum.According to Reuters, freight costs for shipping crude from the U.S. Gulf Coast to Asia have climbed to approximately $30–$35 per barrel, compared with about $5 a year earlier.Security threats around the Strait of Hormuz, higher insurance premiums and longer shipping routes have reduced tanker availability and increased transportation expenses.These developments have made crude produced in North and South America more attractive to U.S. refiners, particularly facilities capable of processing heavier grades.More than 70% of Gulf Coast refining facilities are configured to process heavy crude, allowing operators to take advantage of discounted feedstocks from Canada and Venezuela.The widening price differential between Western Canadian Select and West Texas Intermediate has become particularly important.Phillips 66 executives estimate that every $1 increase in the WCS discount relative to WTI provides approximately $140 million in financial benefits, reflecting the company’s exposure to Canadian heavy crude.Valero executives also highlighted the advantage of shorter transportation routes, particularly when competing against European refiners supplying Latin American fuel markets.U.S. refining margins more than doubled during the third quarter as strong diesel and other refined product prices more than offset rising transportation expenses.Some companies have also benefited from shipping arrangements established before the conflict.Phillips 66 secured more than 40 time-charter vessels, covering approximately 40% of its asset-based shipping requirements, limiting exposure to higher spot freight rates.Valero, PBF Energy, Marathon Petroleum and Suncor Energy similarly arranged chartered fleets before the conflict intensified.The resulting cost advantage could extend into 2027.Marathon expects record Canadian heavy crude processing during the fourth quarter, while management anticipates elevated refining margins through at least mid-2027.HF Sinclair executives also expect favorable crude discounts to persist through 2027, although the outlook remains sensitive to shipping conditions and global petroleum supply.For energy investors, the developments demonstrate how regional crude price differentials can influence refinery profitability independently of benchmark oil prices.Complex refiners with access to discounted heavy crude, reliable transportation networks and favorable product markets may generate stronger margins than competitors dependent on long-distance imports.However, higher freight costs can also restrict export opportunities for Canadian and Venezuelan producers, potentially widening regional pricing discounts.The durability of these advantages will depend on maritime security, tanker availability, refining capacity and the recovery of international petroleum trade.Disclaimer This informational, opinion, and insights article is provided for informational purposes only and does not constitute investment, legal, or financial advice. The views expressed are based on publicly available information and market conditions at the time of publication and are subject to change without notice.