so, there is a oil leak coming from the back of the engine somewhere. but, its not your typical oil leak. it only happens after driving down the highway for 30+ miles, then parking it till it completely cools. then there is this half-quart puddle of oil under my car and i cannot figure out where it is coming from. it only happens when parked after highway driving. i can cruize around town all day long, then park it for the night, and it doesnt leak. its really weird.

clean out the PCV system to eliminate any blockage when under load.