Ford 4.6L 3v, Pennzoil Platinum 5w20 I've noticed that over time the car seems like it's losing a small amount of oil. Over a two-three month period, 1500-2000 miles, it's down about 1/8th of a quart. No noticeable oil leaks or smoke when the car runs. Could this really be the PCV system doing this? I run the car pretty hard if it matters.