SINGAPORE - The United States faces an awkward rival in its first attempts in 40 years to export crude oil - Iran. Iran, whose economy has been throttled by Western sanctions that have halved its crude shipments, is now selling higher quality and cheaper oil to China that leaves little room for the U.S. crude to enter the world's top energy consumer.While buyers in Japan and South Korea have been willing to trial a U.S. grade of the super-light crude known as condensate, China has already locked in annual contracts with Tehran and is not expected to take any U.S. oil in the short-term. With U.S. producers looking to open a trade route to sell surplus condensate from the U.S. shale boom, worries about quality and legal issues have added to doubts about how much of the oil the rest of Asia can take."China gets condensate from Iran, which is much cheaper than that from the U.S.," said a Singapore-based trader with a European trading company. "They might get involved at a later stage but they will not be at the forefront." Condensate won export approval from U.S. officials in June as long as it has been minimally processed, softening a decades-old ban on selling U.S. crude abroad.The light oil can be cracked in a processing plant called a splitter to make petroleum products and petrochemicals, or blended with heavier crude for use in refineries.South Korea and Japan have purchased the first condensate from the United States. Mitsui & Co bought a cargo from Enterprise Product Partners for loading this month and has onsold it to South Korean refiner GS Caltex, sources said.Refiner Cosmo Oil Co has also bought a cargo of U.S. condensate that will load in late August for arrival at the Yokkaichi refinery in Japan in October, a source said.Japan and South Korea, which together account for just over half of Asia's 1.1 million-barrels-per-day (bpd) in condensate splitter capacity, are seen as more open to trying the United States as an alternative supplier.Enterprise has also signed a short-term contract with another Japanese trader, Mitsubishi Corp, with a first loading likely in September.IRAN COMPETITION Asian buyers have been waiting to see if the U.S. oil is suitable and if exporters can price it competitively given it has to be shipped a further distance than competing grades from the leading regular suppliers Qatar and Australia."They are testing the waters so we're not expecting huge volumes this year," said Richard Gorry, managing director of energy consultancy JBC Asia. Showing the competition U.S. exports face, Iran exports about 55 percent of its roughly 250,000 bpd of South Pars condensate output to two Chinese buyers at deep discounts under annual contracts.Since U.S. and European Union sanctions were eased late last year in exchange for Iran curbing nuclear activities, Tehran's exports have risen about 30 percent to 1.25 million to 1.3 million bpd, much of this as South Pars shipments to China.Some of the Iranian condensate could be sold as low as $5 a barrel below Dubai quotes or about $8 a barrel cheaper than Qatari grades.U.S. condensate would likely have to be priced lower than the similar Qatari grades to attract buyers, traders said.Qatar is the biggest supplier of condensate to Asia at about 450,000 bpd, followed by Iran. Australia and East Timor together produce nearly 170,000 bpd, with most of the output heading to Asian markets, according to trade sources. Higher shipping costs compared with the short distance from the Middle East will deter India from buying U.S. condensate, according to sources at Indian refiners.LEGAL, QUALITY CONCERNS Another issue is uncertainty over the future of U.S. regulations on condensate exports.Two U.S. senators have questioned the U.S. Commerce Department's approval, saying exports may violate a ban in place since the Arab oil embargo of the 1970s. Refined products, such as gasoline and diesel, are not restricted."What happens if some ruling appears and penalises the buyers?" asked a trader at a North Asian refiner. "Also, there's not much economics in it so why take the risk?" Asian users are also concerned that U.S. condensates may vary widely in quality as they will be come from fields scattered across shale formations such as the Eagle Ford in southern Texas, from which Enterprise pulls its oil.The U.S. oil is expected to be more commonly used as a blend stock by refiners, limiting the amount available for 350,000 bpd of new splitter capacity coming online in Asia this quarter.