The pilot reported that during the cruise phase of a cross country flight, the oil pressure and oil temperature indicator readings dropped to zero. The pilot decided to make a precautionary landing at a nearby airfield. The airplane touched down on the runway and the right main landing gear leg fractured just above the wheel attachment and the wheel separated from the airplane. The main landing gear leg collapsed and the airplane exited the right side of the runway. The airplane sustained substantial damage to the fuselage. According to the maintenance logbook entries, the right main landing gear leg had fractured at the point of a previous repair. The airplane had larger tires and brakes installed after the time of the repair to the landing gear leg. The cause of the fluctuations in the oil temperature gauge and oil pressure gauge were not the subject of this investigation. The pilot reported no preimpact mechanical failures or malfunctions, aside from the gauge indications, that would have precluded normal operation.