Brent jumps 4.6% to $102.55 on a third US carrier; its gap over US crude widens to $9.31

Brent crude rose about 4.6% on Thursday to $102.55 a barrel, and US benchmark West Texas Intermediate gained about 3% to $93.24, CNBC reported. The trigger was a Wall Street Journal report that the US is sending a third aircraft-carrier strike group to the Middle East, along with Marine Corps ships and up to 10,000 more troops, all expected to arrive by the end of November.

According to the Journal, as cited by CNBC, the USS Theodore Roosevelt left San Diego on Sunday, joining the USS George H.W. Bush and USS George Washington already in the region. CNBC also cited a Reuters report that PetroChina canceled several gasoline and jet fuel cargoes planned for October to protect China's domestic supply, which CNBC said it could not independently verify.

The strait is less open than the export numbers say

The carrier news landed on a market already reminded that shipping through the Strait of Hormuz is not back to normal. Three Liberia-flagged tankers were hit by unknown projectiles while transiting the strait on Tuesday and Wednesday, shipping intelligence firm Marisks said, according to Reuters as reported by OilPrice.com. The ships were the products tanker Al Ruwais, the supertanker Mersin Prosperity and the Aframax Sinbad. One attack started a fire that was put out, with the crew reported safe.

That matters because the case for lower prices in recent weeks rested on crude flows recovering. As we reported earlier, crude exports from the Gulf had climbed back near pre-war levels while refined fuel shipments had not. A UOB note cited by CNBC made the same point on Thursday: crude is flowing, gasoline and other fuels are lagging.

The number behind the number: the Brent-WTI gap

Brent rose more than WTI, by our arithmetic from CNBC's figures about $4.51 a barrel against about $2.72. That pushed the gap between the two benchmarks to $9.31, from roughly $7 to $8 on Wednesday. Brent is the price of seaborne crude that has to move through contested waters. WTI is priced inland in the US. A widening gap says the market is pricing a risk to shipping, not a shortage of oil in America.

That is a cushion for US refiners, which buy the cheaper WTI-linked barrels. It is not much of a cushion for US fuel buyers. Diesel and gasoline trade on global product markets, and the US has already threatened Europe with a diesel export ban because product, not crude, is what is short.

Who it hits: what 11 cents means

A barrel holds 42 gallons, so Thursday's $4.51 move in Brent is about 10.7 cents a gallon of crude cost. Pump prices do not move cent for cent or on the same day, but that is the direction of travel if the move holds.

It lands on diesel that is already expensive. The EIA's national average for on-highway diesel was $6.382 a gallon on Sept. 28, down 14.7 cents on the week but $2.628 higher than a year ago. A trucking company buying 10,000 gallons a month would pay about $1,070 more a month at 10.7 cents a gallon, on top of roughly $26,280 more a month than a year ago.

Small carriers are the most exposed, because many pay pump prices weekly and pass on fuel costs to shippers only with a lag. There are 24,679 independent trucking and freight companies listed on CheckThisBiz, with the most in Texas (2,868), California (2,828) and Florida (1,916). Our trucking playbook covers fuel surcharges and cash flow.

What traders are watching: whether the carrier deployment changes the pace of US-Iran talks, and the EIA's next weekly diesel price on Oct. 6. Track crude on our oil chart.

Sources: CNBC, citing The Wall Street Journal and Reuters; OilPrice.com, citing Reuters and Marisks; EIA Gasoline and Diesel Fuel Update; business counts from CheckThisBiz. Spread and per-gallon figures are Chronicle calculations. This is market information, not investment advice.