Oil import of China from US will have 5% new tariffs from the first of September. It means that the cost of oil for Chinese refiners will increase 3$ per barrel. Therefore Sinopec as the biggest refinery both in China and Asia asked to be exempted from this new tariff. Totally 8 million oil barrels will be exported from US to Sinopec on October and September. If the Sinopec cannot be exempted from this new tariff, it will keep the cargo in customs or will send it to other destinations.
On the other hand Iran oil can be exported to China at best prices as its freight rate is affordable. According to analysts, China and US relation is at the worst situation of cold war so it is not unlikely that China starts to buy oil from Iran, meeting the requirements of its refineries as well as challenging one of the most significant policies of Trump! If China decides to do it, then oil price will experience another plummet! Using the Iran oil as an arm against Trump, can reduce the oil price 30$ per barrel!