You are correct that I am not currently using the factory oil cooler connection above the factory oil filter location. It is indeed currently blocked off. It does in fact run from the adapter at the factory oil filter location out to the remote mount filters and then through the cooler and back to the adapter at the engine.
To give a little back story on how this all got started...
I had a small intermittent ticking on the drivers side of the engine which I attributed to lifter ticking. It would sometimes occur immediately after start up and tick for a few seconds and then stop. It also sometimes would start ticking after sitting and idling for 20+ minutes and after driving again it would go away.
I decided that I would replace the oil pump and O-ring on the pickup tube, along with a new timing chain while I was that far in. I installed a Mellings HV/HP pump. My 5.3L is an LMG (flex fuel) engine which came from the factory with a HV oil pump. I decided since the truck had 185k miles at the time that a little bit extra oil pressure wasn't a bad thing so I installed the HV/HP pump which was supposed to increase pressure by 10%.
After getting everything put back together all was well, no more lifter ticking BUT after driving it for a few days I got a check engine light... pulled the code and it was oil pressure sensor out of range. Ok no big deal. Pulled the old switch and screen and installed new. Drove a little bit same issue.
Now mind you prior to me installing the new oil pump my oil pressure would be 45-50 on a cold start and 20-25 hot idle.
After the new oil pump I would see 70-75 cold start and 60-65 hot idle.
Needless to say, the ECM didn't like seeing the oil pressure that high because it didn't fall into what it was programmed to see as "normal range".
In an attempt to lower the oil pressure enough to make the ECM happy I installed this dual filter setup and the oil cooler using the factory oil filter location, ON PURPOSE, to try and lower the pressure a bit by introducing some restrictions into the system.
While it did lower the pressure a little bit, it still was not enough. I contacted Black Bear Performance to see if they could adjust the parameters in the ECM for the oil pressure range... they could not.
I ended up buying a 2' long oil pressure sensor pigtail extension and installing a resistor inline on it and plugging that inline between the oil pressure sensor and the trucks wiring harness to "lower" the oil pressure that the ECM and gauge "see". This does not make the oil pressure gauge non functional, it still functions just as it always has, it just reads about 15 PSI lower than the actual oil pressure. The ECM is happy and I don't have a check engine light which would keep me from remote starting the truck, which I use all the time because I am a big proponent of warming up a vehicle before driving it.
So I SERIOUSLY doubt that it is causing a problem with LOW oil pressure.
The cooler I am running has 1/2" NPT fittings. This is a picture of the cooler I have.