RuBiCaNT

Wednesday I noticed my Subaru was smoking after journeys lasting longer than 10 minutes. I narrowed the smoke down to someplace under the air filter box. The car is a 2001 Outback wagon with the SOHC 2.5L and 4 speed AT transmission. My guess and I really have not seen exactly where the smoking originates from is that it's an AT cooler line that has cracked or weakened. When the fluid gets hot it expands and forces a small pinhole of fluid out on a hot part of the car and thus the smoke. I don't think its oil since the smoke is in the rear of the car and doesn't smell like burning oil. The oil level is perfect. I don't think it's coolant because there is no sweet smell that you typically get with burning coolant. What does everything think? Saturday I will be getting a better look to see exactly where the smoke is originating from. There are no driveability issues, no CEL's or anything of that sort. Thanks in advance.