On December 24, 2010, about 1440 central standard time, N921DZ, a Columbia LC41-550FG, single engine airplane, received minor damage after an off-airport forced landing near Milsap, Texas. The solo pilot was not injured. The airplane was registered to and operated by a private individual. Instrument meteorological conditions (IMC) prevailed at the time of the accident and an instrument flight rules (IFR) flight plan had been filed for the 14 Code of Federal Regulations Part 91 personal flight. The airplane departed Bourland Field Airport (50F), Cresson, Texas, about 1415 destined for Phoenix Deer Valley Airport (DVT), Phoenix, Arizona. The airplane was at 9,000 feet mean sea level (msl) in a climb to 16,000 feet msl when the pilot noticed that the engine was not producing full power and the engine oil pressure had dropped to an unacceptable level. The pilot declared an emergency and requested a descent and vectors for an instrument approach to runway 31 at Mineral Wells Airport (MWL), Mineral Wells, Texas. The airplane was in IMC when the “engine quit” about 3,000 feet msl. The airplane broke out of the clouds about 500 feet above ground level (agl) and the nose gear collapsed during the engine out landing in an open field. The airplane had recent maintenance performed when the engine was partially removed to replace the starter adapter. Aircraft logbook entries show that the maintenance activity was inspected after completion and that a ground run of the engine was satisfactory with no leaks noted. The pilot reported that after the maintenance was complete he flew the airplane twice and had no leaks and no problems. A teardown examination of the engine showed there was a breach in the crankcase with several areas inside the engine that exhibited lubrication distress, thermal distress, and mechanical damage. There was mechanical damage to several connecting rods and to the crankshaft and counterweight assembly. The examination revealed no other preincident mechanical malfunctions or failures that would have precluded normal operations. The reason for the in-flight loss of engine oil could not be determined.