Hiring a supertanker from the US Gulf Coast to Asia now costs more than $80 million — roughly $40 a barrel — against $10–15 million at the start of the year. That quintupling-plus move in freight is stranding heavy crude across North and South America, cutting exports to Asia and Europe and splitting the global oil market while Brent holds above $100 a barrel.

The number that lands hardest: shipping crude from the US Gulf to Europe ran an estimated $46 million, or $24.50 a barrel, last week including ship-to-ship transfer costs, according to Signal Maritime analyst Georgios Sakellariou. Before the Iran war broke out in late February, the same voyage cost $6.5 million, about $4 a barrel. As Reuters noted, it is now more expensive to hire a tanker from the US to China than to launch a rocket into space.

Why is heavy crude piling up in the Americas?

Dense heavy crude, the grade that Asian, many US and some European refineries are configured to run, is stacking up because freight has priced the barrels out of their export markets. The economics that normally favor heavy grades — cheaper feedstock, better refining margins — only work when shipping is affordable. Right now it isn't.

"It's all freight," said Scott Shelton, an energy specialist at TP ICAP. Venezuela, the US and Canada all produce more oil than they consume, he noted, so they depend on exports to Asia to balance their crude books. "You need a ship and the price of ships are going up, and the availability of ships is going down."

The supply side has compounded the problem:

• Venezuelan exports have surged since the US captured former President Nicolas Maduro in January and began pushing to reactivate the country's oil sector.
• Canadian output is at a record.
• Washington has released more than 130 million barrels from its Strategic Petroleum Reserve.

Demand-side relief isn't coming from US refiners, despite record diesel prices that should, in theory, make cheap heavy barrels irresistible — heavy crude yields more diesel than lighter grades. But Gulf Coast refiners have already bought as much as they can process, analysts and traders said.

What are the numbers behind the refining bottleneck?

US refineries have operated at about 93.5% of capacity on an average weekly basis so far this year, according to the Energy Information Administration. That is the highest utilization in 28 years, driven by refiners maximizing output to cash in on record diesel prices.

Even at those rates, they can't absorb the surplus. The refineries are complex and geared to run a heavier slate, but only up to a set percentage of total capacity. Many are also configured for offshore Gulf of Mexico grades such as Mars Sour rather than Canadian or Venezuelan oil, which must be blended with lighter feedstock before processing.

An analyst quoted by Reuters, Irwin, put the dynamic plainly: "While Venezuela and US emergency barrels have been a factor for months now, leading to near maximum US coker utilization, high freight is now a further headwind to shipping these barrels east and is forcing heavy sour storage builds in the Americas." Cokers convert residual crude into feedstocks for diesel and gasoline production, and a heavier slate forces them to run harder.

How far have heavy grades discounted?

The price signal is unambiguous. Flagship Canadian, Colombian and Ecuadorian heavy grades have all eased more than $10 a barrel to six-week lows, according to price reporting agency Argus Media:

• Western Canada Select, excluding shipping and insurance: around $74 a barrel on Thursday
• Colombia's Vasconia: around $84
• Ecuador's Oriente: around $76
• Venezuelan crude, ex-shipping: around $74.50, per two traders

Meanwhile buyers in Asia and Europe face the mirror image — supply shortages and benchmarks above $100 — because the arbitrage routes that would rebalance their markets are shut by freight.

What does this mean for shipowners and charterers?

Ship-to-ship transfers in the Gulf of Oman are tying up vessels worldwide, and that tonnage attrition is the engine of the rate spike. For owners of VLCCs, the regime is a windfall: the US Gulf–Asia trade has moved from roughly $10–15 million per voyage to more than $80 million inside a year. For charterers and oil traders, long-haul heavy crude economics are effectively broken at $24.50–$40 a barrel of freight, which is why cargoes are staying home and storage is building instead.

For refiners in Asia and Europe configured for heavy slates, the shortage is structural, not cyclical — they cannot easily switch to light crude without sacrificing yield. US Gulf refiners, already near ceiling, have no room to rescue the stranded barrels regardless of price.

The forward path hinges on vessel availability in the Gulf of Oman rather than on any crude-side fix: until transfers stop tying up tonnage, freight stays the marginal price-setter, and heavy sour discounts in the Americas widen further while Asian and European buyers keep bidding above $100.