This 1HDFT motor has 100k miles (mas o menos). The factory oil breather (off the top of the valve cover) is plumbed into the intake manifold.
20 years of sending fumes into the intake results in this mess.
Ive never seen that in a 1HZ and I have had several high klm air intakes in my shed over the years. I have one there now that did 143000klms before the engine spun a bearing and its as clean as a whistle.
These are probably JDMs that spent half their running time sitting in heavy traffic smouldering away