On May 7, 1998, about 1920 central daylight time, a Piper PA-28-140, N8218N, registered to a private owner, crashed during a forced landing, near Luvurne, Alabama, while on a Title 14 CFR Part 91 personal flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged. The private-rated pilot and two passengers were not injured. The flight originated at 1800 and was en route to Headland, Alabama. The airplane was in cruise flight when the pilot reported to ATC that he had oil on the wind screen, and was losing oil pressure. According to the pilot, he had just descended to an altitude of 2,000 feet, when he noticed that the, "...fuel pressure was maxed out." He checked to see if the electric fuel pump was "ON," and it "wasn't." At this time, smoke started filling the cockpit and he opened a vent window. He then checked the oil pressure and temperature, and found them to be "okay." He then started to look for a place to land and declared an emergency with ATC, telling them that he had "smoke in the cockpit." At the same time, the pilot said, "...I could see a little bit of smoke coming from the front of the nose cowling. Within a minute, the oil started to hit the windshield, "I knew I was not going to see much longer." He asked ATC for vectors to the nearest airport, and was told that there was an airport at his 12 o'clock position, 4 miles ahead. The pilot said because of the oil on the windshield, "...I couldn't see anything, so I slipped the airplane so I could see out the left window...when I did the aircraft started to loss altitude...the oil from the left window started to flow down the left side of the airplane...now I can't see out the front...or left side window...with the airplane in a left slip I am loosing altitude. I was at 1,300 feet. I looked at my gauges...oil pressure was at 40 or 50...temp was at 190 degrees...RPM was dropping...I had to put this airplane down in a field...or it's going to crash into the trees....I saw a road...I turned the airplane to a left downwind over a lot of pine trees along the road...I was about 600 or 700 feet. I saw power lines across the road...I turned left base for the road...the stall warning came on...once the stall light came on...I had to pull back on the yoke to keep my altitude up to clear the power lines...when I did clear the lines I had to lower the nose to get back some of my airspeed...I missed my final for the road and the only thing left was a small field...I was about 60 feet...I turned the engine off...lowered the nose real quick and headed for the field. The field was too short to land in from that altitude...around 10 to 20 feet off the ground, I pulled back on the yoke to kill my airspeed, and let the airplane fall into the field...the airplane hit the ground on all three landing gears at one time, bounced about 20 to 30 feet...." The pilot stated that he had rebuilt the airplane's engine and reinstalled it on the airplane in May 1998, and had about 4 flight hours on the reinstalled engine before the accident. The pilot said that after reinstalling the engine, and on the first run up of the engine, the oil pressure "was too high." He reset the pressure from a reading of 110 psi during the first run, to a setting of 75 psi. He then flew the airplane for 10 minutes, and said "everything looked good." On the day of the accident, he flew to Selma, Alabama, and had no problem during the flight. After the accident, an examination of the engine and airframe revealed that the forward nose seal, on the engine had come loose, and was the source of the oil leak. The pilot said that the seal came loose, "...due to high oil pressure on [the] first run up." According to the FAA Inspector, the pilot said that after he made the first engine run and had readjusted the oil pressure, he should have rechecked the seals, and he did not.