I don't know Cap it would be interesting to find out what the fuel consumption is compared to a 4 stroke diesle. They stopped making them for a reason so I guess they didn't compete.
Some of the Petters were 2 strokes like this one at the museum of internal fire in Wales
http://www.youtube.com/watch?v=1IE7YBJ2eXwThe semi diesels are 2 strokes and the german video apears to be a semi diesel as well.
I don;t know exactly how they are lubricated but we saw a video of a runaway semi deisel here a while back.
Here they say too much oil in the crank case so it could be they havea wet sump and use the crank case for scavanging.
Peter can you clear this up?