Oil leak

This a wierd one, after a long journey when I stop the van and switch off the engine, the engine leaks about a 1/4 cup of oil on to the road, but it doesn't seem to leak when its running, well it does but only a few drips here and there anyone any ideas what could be causing this ?

 

Despite appearences, it's leaking when running and stops when you stop the engine. It gets blown into the recesses when the engines running then falls out when you stop.

 

crankshaft oilseal

 

or push-rod seals

 

first guess, pushrod seals

 

Thanks Guys,
One more music festival and one more camping trip and Maggie will be "sorn"-ed for the winter, will drop the engine and re-new all the seals and probably the pushrod tubes as well.