Pilot of C182 lands to investigate low oil pressure indication. Finds no obvious reason and takes off only to have engine fail catastrophically.

Narrative

Borrowed a friend's C182 that needed to be flown. Aircraft had about 15-18 hours since a teardown inspection and had not flown in the past 120 or so days. Asked a former student to go for the ride. Flew for about 1 hour when I noticed the fuel gauges reading erratically and oil pressure on the bottom of the green. Thinking we may have left a fuel cap off; I initiated a landing to check the caps and look if we had an oil leak. Engine oil temperature and CHT read normally through the descent and landing. Landed uneventfully. Let the aircraft sit for 5 or so minutes; checked the fuel caps; oil cap; dipstick oil lever and under the aircraft for any sign of oil leak. None found. The engine appeared dry. There was a 'paint like' smell but I attributed that to the teardown inspection. Ran the aircraft up -- everything checked out well with the exception of the oil pressure still hovering at the bottom of the green. Having dealt with this situation before (low or high oil pressure) after engine work; I figured the spring for the oil pressure needed an adjustment as I had seen done in the past. We taxied out; climbed to 4;500 FT. When we started to see a drop in oil pressure and smoke; we flew for another 3-5 minutes in an attempt to land at ZZZ. The engine then came apart; and we had engine stoppage. We landed uneventfully in a field that is used periodically by aircraft on skis. No damage to the aircraft or persons on board. Human factors/experience: Other instruments reading normal gave me false encouragement. I feel that my experience actually hurt in this case. It helped with the landing; but hurt with regard to my aeronautical decision making.