Oil stain on engine

[AnnetteOY]

No I am on a road trip and at my last fuel stop I noticed this oil stain on my engine. I have a 2003 Dodge coming 3500. Any suggestion what it is? And can I continue on my road trip for the next couple days with this until my destination?

 

[srv1]

Welcome O troubled one.To me it looks like a valve cover gasket leak.I would ck. your oil level.maybe buy a qt. or two and keep an eye on it and if any is on the ground after parked.It may smoke a little if its getting on the exhaust.I do not own a diesel but this is what I'm seeing.Maybe someone with a diesel will chime in.Happy trails.