.... when I noticed that the oil pressure had begun dropping. I immediately turned towards the nearest airport, which was Kingston, NY. Actually there was a private grass strip I would have landed on if I had to, which was the Old Rhinebeck Airport, but they had an airshow going on. Oil pressure kept sliding down and so did the oil temperature, probably because the thermocouple had become uncovered.
I came in on a 45deg right base to Runway 33, nobody was in the pattern (I'd have told them to get the frak out of the way if there was anyone there). I pulled the mixture out when I had the field made and landed. I came in rather hot; for that runway, the risk of running off the far end and maybe ground-looping was preferable to the risk of landing short. I made a turnoff without braking and coasted to a stop on the taxiway clear of the runway.
When I got out of the airplane, the tailwheel was soaked with oil and oil was dripping out of the cowling. Of the seven quarts that were in there when I took off 35 minutes before, a gallon of oil had been lost. Oil pressure never dropped completely to zero and the engine sounded fine. Some nice men helped me push the airplane to a tiedown and an hour later, another nice man gave me a lift back to my home airport in his Cherokee.
The cause was a split seam in the oil cooler, which itself is brand new (installed in May). The oil cooler will go back to the maker and then we shall see. I hope to have a new one back and be flying next week.
I've got over 1,200 hours of time, virtually all of it in single-engined aircraft, and this was my first emergency landing for mechanical reasons.