MELBOURNE, May 1 : Oil rose on Friday as efforts to resolve the Iran war remained at an impasse, with Tehran still blocking the Strait of Hormuz and the U.S. Navy blocking exports of Iranian crude.  Brent crude futures for July were up $1.04, or 0.94 per cent, to $111.44 per barrel by 0421 GMT, while West Texas Intermediate futures had risen 41 cents, or 0.39 per cent, to $105.48 per barrel. Both benchmarks have posted gains across four straight months, with Brent's June contract, which expired