The pilot reported that the purpose of the flight was to conduct flight testing of the amateur-built experimental airplane. The pilot was also the owner/builder. He stated that while conducting some clearing turns in preparation for slow flight testing, he observed an oil pressure warning on the engine monitor. The indicated oil pressure was zero. He immediately turned toward the airport and reduced engine power to idle. About 60 seconds after the oil pressure warning, the engine lost power completely. The pilot established best glide airspeed and set-up for a forced landing. He noted that he overshot the first field he had selected, but then settled on a second field. The airplane clipped two sets of trees during the approach and struck a wire fence during the landing. The pilot estimated that the airplane slid 20 feet after touching down. A post accident inspection revealed a failure of an oil hose. Specifically, the return hose from the oil cooler had a 1-inch longitudinal split at a bend in the line. The pilot commented that he might not have properly accounted for the compound S-bend at that location on installation. The airplane had accumulated about 5.4 hours at the time of the accident.