Chinese state oil giants are back scouring the market for Russian crude, four months after halting purchases due to the U.S. sanctions on Rosneft and Lukoil, as China aims to offset losses of supply stuck in the Strait of Hormuz. The U.S. last week issued a waiver allowing purchases by April 11 of Russian crude already loaded on tankers in a bid to calm the global oil market amid the biggest supply disruption in the history of oil markets. Chinese state giants are taking advantage of this waiver and are now looking to buy Russian crude…