I think that would be just putting a band-aid on the issue. If you do that it could cause even more problems... too thick of an oil and it won't get into everywhere that it needs to be very well then really expensive stuff will start hitting the fan.

The valve cover bolts should only be at 17 lbs. Just enough to snug the gasket otherwise you risk leaks and breaking stuff.

Best is to get to the root of the cause. Without it being a milkshake still... I wonder if you may not have clogged screen in the pan or something that would prevent oil from circulating up into the system like it should. Or the oil pump itself. Im just spit-balling here... I could be off. It's obviously not cracked because you would still have coolant in the oil and vise versa so it has to be another issue.

 

all that extra ZDDP (Zinc).... is so delicious for our old flat tappet motors too

 

So it's looking like worn bearings are most likely. I don't have the time, tools, space, or experience to do a rebuild so looks like I'm going to have to do an engine swap. Does anyone have a good source for an engine? Do remans tend to have the same bad 0331 cast? I don't want to waste my aftermarket cylinder head but labor on a short block install is outrageous in this area.

 

When I when looking for a rebuilt engine for my WJ 4.0L, I asked that specific question about the 0331 head. I was told by several companies the the head is inspected and tested before being used in a rebuild, but whatever the engine can in with, it went back out with that head if it was good. That was not good enough for me, so I bought a short block and reconditioned my "Clearwater" head to put on it. I asked about getting a later model engine with the "TUPY" head on it and they told me I'd have to give them my block number so they could match it for the new rebuilt one. Again, no guarantees. You are much better off getting a used engine or having yours rebuilt locally. Just my opinion. You're not going to find a Cherokee 4.0L with anything but a 0331 head unless it has already been swapped. The "TUPY" wasn't produced until early 2002.

WARNING! Do not use Rotella T6 in a brand new engine! The clearances are too tight for a 5W-40 oil. My 4.0L sheared the oil pump drive after I did my first oil change after the rebuild. My mechanic used Pennlife 5W-30 High Zinc for break-in. Valvoline Max-Life 10W-30 has about 600 ppm zinc in it and should work fine.

 

Unfortunately none of the shops in this state even offer rebuilds cause labor is so high. Will probably tow it out of state just to get the swap done. I have the clearwater head and short blocks look a bit more affordable, but I guess it'll depend on what they charge extra in labor for the install

 

IF you have the time and place it work in it, you could have the short block shipped to you and install the head on it yourself, then take it to someone to install it in your jeep, saving some cash. I would recommend getting the head reconditioned (ie; valves and seals) for about $200 before installing it.

In my state, racing engines and classic cars keep machine shops in business, so it takes a long time to get a simple layman's rebuild done which is why I didn't go that route either. I will admit they did my head in a week because my mechanic took it to them.