Chevron does not report a comparable, standalone refining-margin figure, but it reported Friday that its downstream earnings more than quadrupled from a year earlier to $4.9 billion, with the company citing higher margins on refined-product sales.

That's amid tight supplies of refined fuels and pressure on refinery output globally, despite oil firms reporting this week that they are running their facilities near capacity to try to meet demand.

Along with soaring refined product margins, higher crude oil prices have also supported earnings at some integrated oil majors, which operate both upstream oil-and-gas businesses and downstream refining operations.

Their profits have climbed back toward levels last seen during the energy shock of 2022, following Russia's full-scale invasion of Ukraine.

The earnings spikes are in sharp contrast to consumers facing higher energy prices.

Some analysts say political efforts to tackle prices — release of emergency diesel stockpiles and a U.S. deal with Russia to supply more diesel to the global market — may have only a limited impact unless they materially increase available supply, demand weakens or global tensions ease.

Raphael Portela, director for corporate strategy and analytics at energy consultancy Wood Mackenzie, told CNBC that crude oil barrels were still "getting out of the Gulf" amid the war, but "at a steep freight premium," while "the diesel and jet fuel those barrels would have become largely aren't."

"Russia's refinery outages and export ban have taken a second slug out of the global pool," he added.

He listed what would have to happen for the crunch to end: "Product supply coming back, based on greater crude availability to the global refining sector: Gulf refineries restarting and Russian exports returning.

"A Hormuz settlement would hit margins quickly on sentiment, but with inventories this depleted, the physical tightness carries well into 2027."