In the initial few hrs of our trip to the canyons, a discoloration streak appeared on the top cowl, from the right inlet, next to the spinner. There was not really enough to wipe off. Just discoloration of the primer on my cowl.
I took the top cowl off. Everything appeared dry as a bone. I've seen prop grease emanations on an Arrow before. My prop is dry as far as I can tell. No streaks.
It grew enough to lightly spatter the passenger side windshield.
Cleaned the cowl and canopy. Next flight got a slight wisp on the canopy. Cleaned it. The total time from start to finish was roughly 4 flight hrs. Been good for the next 20 hrs. The stain on the cowl is still there but it is dry to the touch. The canopy is not getting any spatter that I notice anymore.
Dunno'. I'm still guessing a burp of prop grease because the canopy looked the same as the Arrows did.
BillL,
I wondered about inlet backflow next to the spinner and for some short time thought this was oil coming out my alternator blast tube (I have a slight seep at the front of the oil pan so oil is available) because this tube inlet is pointed at the right spot on the cowl. BUT, the inside of the blow tube feels dry.
On an Occams razor side note, this 4 hr event was after the plane sat outside overnight in a rain storm from hades. First time. She's a hangar babe. I wonder if the high winds and rain moved some oil or grease inside the cowl to a new place?