I know this is an old thread, but I’m replacing mine this weekend, noticed a spot the other day where I parked, popped the hood and oil was in the valley, 2018 with 90k miles, I guess it lasted longer than some

 

I'd highly suggest replacing with a new one that is a complete filter housing and cooler unit already installed. The Dorman aluminum I got came like that. I disassembled the old one in an attempt to find the source of my woes and getting the cooler off and dealing with those gaskets is just a whole other step. In the end, best I could tell, mine was just weeping from between the cooler and lower filter housing assembly. It's not a terrible job, but definitely gets old working back in that location. I struggled with the electrical harness at the rear of the manifold and ended up just leaving it. I was able to get the lower manifold up and off to the side enough to do what I needed to do with the oil filter housing....though it was a bit aggravating cuz all of the dirt/dust that would drop down if i accidentally bumped the manifold. I got things cleaned well enough to tape over all the ports in the head asap.

 

I got the dorman complete with the cooler

 

Here are the torque settings for those cooler - get your 3-4 year old grandchild to tighten it as hard as they can using a 1/4" drive ratchet. Seriously the son does his 2016 and he lubes the thread and new o-ring with a thick oil like gear oil and hand screws it in till it stops then with the socket and ratchet goes 1/2 turn more. Done and never leaks. Was a similar experience when I had my 2007 5.9 Cummins for the top of the diesel filter housing.

 

Well, a little over two weeks with no oil drips, amazing how much oil is in the valley before it shows up an obvious leak, had probability been seeping for a great long while before I noticed a leak

 

Y, I thought the same. The pictures above focussed primarily on the unit itself so in the thread I started I tried to take a couple pics so folks could understand how deep that valley was, and with the various "bulkheads" it had, how much fluid it was really holding in there before you had any signs of an issue.