You wont see oil pooling in the intake unless the gasket is VERY bad. The plenum gasket is bad though either way. They only last MAYBE 30k miles. They did a recall on them many years ago, fixed them, they failed again, Jeep did nothing. The only way to properly fix it is ti use the aluminum belly pan. Just replacing the gasket is pointless. When i bought my 5.9 i got a stack of receipts with it. 5 receipts for the plenum gasket in 163K miles plus the first one done under warranty at 36k miles. I replaced it again which makes it the 7th time but i did it right using the aluminum plenum pan and a Mopar gasket set. No problems yet and that was over 30k miles ago.
Platinum 5.9 2.25" engine pipes 3" Magnaflow cat, 3" Hooker Aerochamber, 3" tail pipe, Ported kegger, 52MM Throttle Body, 24lb injectors, K&N drop in filter, Cast JEEP valve covers, MSD coil and wires, All new 6 piece clear light kit, 255/65/16 General Grabber HTS, 242 conversion, XJ u-joint front axle shafts