Look in the intake valley for signs of an HPOP leak. It would drip down the back of the engine and get blown off to the rear. When my HPOP was leaking camper always took an oily hit. I fyou can't get to the HPOP repair right away rig a high edged baking pan up under where the drip is to catch the drips. It will self-drain when you hit the brakes hard!