Hi, with so little detail it is guesswork as to the cause of the failure. If the motorhome had a service and cambelt renewal then set off on its journey through France it had probably clocked up less than 1000 miles with the new oil. For the oil to be the cause of the failure after such a short mileage it would have had to be way way way off spec. Metal in the sump would indicate main or big end bearing failure. Incorrect oil levels could cause this, too little oil would cause a low pressure but would trigger a warning light, too much oil in the sump puts excessive load on crankshaft and conrods and can cause bearing damage. My Mercedes has a high oil level warning, don’t know about Fiat’s. Another possibility is if the motorhome had gone through a number of regens on the dpf the oil could become contaminated with unburnt fuel oil. That’s my best thoughts.
Regards David