DEN83LA121

During a night flight, oil began spreading over the windshield & heavy smoke came in the cockpit through the cabin heater. The plt opened the cabin windows, reduced power & turned back toward the arpt. The oil pressure dropped to 5 PSI & the plt descended to land on a road which could be seen on the moonlit night. Reportedly, the engine began to 'rattle' as the acft neared the ground. The plt lined up with the road, but lost sight of it momentarily due to clouds obscuring the moon. Just before landing, he saw a guy wire & maneuvered the plane to avoid a collision. The acft stalled & hit a ditch, then the nose & left main gear sheared off. The acft continued thru bushes, hit a fence & nosed over. An investigation revealed that 2 oil lines had rubbed together until 1 had worn thru. The oil lines should have been protected by a rubber spacer & a clamp. Either the clamp had failed or had not been installed. Subsequently, the rubber spacer had moved & allowed the lines to rub together.