And I found this:In the oil filler tube. It's not on the dipstick or anything, Just in the tube. Anybody know what it is? And also, The oil was very old.... It was pitch-black. The car is a 99 Jeep Grand Cherokee Limited with the 4.7l V8, It has 136k on it.
The foam is usually associated with moisture. It's caused by condensation, or actual water intrusion, so the air circulation theory is plausible.I have the 3.7L V6, its the 4.7L with 2 cylinders lobbed off. I get the same in the oil filler tube. Your PCV could be perfectly fine. Look at the oil filler tube, no air is circulating inside that, likely why you get the emulsified oil there. Same with the oil filler caps on a lot of engines, its the one spot the air doesn't circulate as well, so it collects there.