We had an Irish built soil screening plant called a "PowerScreen"
It had a 3 cylinder, air cooled Lister Petter diesel in it. Put out about 30-40 horsepower I think. It ran a hydraulic pump. That little engine ran, and ran, and ran, and ran... Low on oil, dirty oil, dirty air filter... It didn't care...
When dad sold the company, the screening plant was 25 years old, and had amassed somewhere north of 20,000 HOURS! And, as far as I know, it is still going. I think they sent it to an Amish fellow in central PA, who was a Lister specialist, and had it "freshened up". I think it only cost about 500 bucks. And she is still going...
I would give my left arm for another motor like that...