Buddy of mine has a 96 jeep XJ Cherokee with the 4.0L I-6.

He is getting oil into the water, but no water into the oil.

My first assumption is like any other, must be a head gasket! But I don't know the 4.0 jeep engine.

 

Here is diagram of the oiling:

http://www.jeepforum.com/forum/attac...system-4.0.jpg

There is no pressurized oil going through the head gasket. A leak that allowed draining oil to enter the coolant via the head gasket would also allow coolant to enter the oil. Usually.

A cracked head could pass it either way.

A cracked block might be more prone to a "one way" leak.

How much oil is he getting in there? A trace or a ton?

 

That's what I was afraid of.

He says not much but I haven't seen it

 

If it's just a little brown sludge on the cap, try a little clean up or flush if you want and watch it. But if it's measurable amounts regularly, get your tools out....

 

He flushed it today and changed oil so we will be keeping an eye on it