Crude oil prices eased in Asian trade, today, after surging the day before as investors weighed the effects of China's announcement that it would allow a more flexible yuan currency. New York's main futures contract, light sweet crude for delivery in July dipped 42 cents, to 77.40 dollars a barrel. London's Brent North Sea crude for August delivery fell 45 cents, to 78.37 dollars a barrel.Analysts today said oil prices retreated on signs that any strengthening of the yuan would be gradual.