Hello all, looking for assistance as I am planning on selling a '09 silverado for a relative who had to leave the country in an emergency. I'm not familiar with chevy's and noticed it has a slow oil leak. It is between the engine and transmission, I attached a picture. If I wipe it clean, it doesn't leak (at least not within 20') but if I start the truck it starts leaking. Not much as the oil is within the markings of the dipstick but then again I only drove it 100 miles after I swapped the battery.

has anyone had this issue? I normally chase leaks from the top down but i dont want to have to tear off the intake and whatever else. Likelyhood its just the oil pan gasket?

thank you