I thought you had mentioned the oil was leaking from the oil filler cap..I would replace the cap(because it is cheap), if it wasn't the cap then the only other thing that could be leaking at the oil filler cap would be the VC(high dollar and costly to do the job).
So without further adue..I would throw an oil filler cap at it..
Sometimes....just sometimes..Its less costlier to throw a less expensive part at a problem, then it is to troubleshoot(troubleshooting is costly and sometimes carries a minimum fee).
Surely dont wont to get into taking it to the dealer or a ametuer and them sell you a VC right off the bat, because the oil filler cap would not bring in enough labor costs, so I will sell him a VC job.