2012 4.0 Full Coolant Swap

>>>> yes theres only a few ounces of coolant in the block itself 6 ounces would amount nottoo much once you added the new stuff, people saying they are getting gallons out of the block are lying to you, <<<<

Now that is a bit harsh. I doubt anyone is "lying" because when I do mine, I get more than a few ounces and less than gallons, and I am not lying.
Using 1/4 inch extensions and swivel sockets make the job much easier than some in this thread have experienced.
I am the "experiment" when it comes to coolant. I have an early 05 with 154K miles and I replace the coolant every 20-25K miles in hopes it will keep the head gasket gremlin away. New coolant keeps the acid level low and may prolong or eliminate the head gasket problem completely. That is the experiment.

 

FYI, also don't overlook the OUTSIDE of the radiator and condensor coils
Years of impacted bug splatter goo, diesel smoke and road grime can clog the airflow through the fins.
It is very difficult to clean without mashing fins ( no pressure washer). I use degreaser like Simple Green and engine degreaser spray, let it soak, low pressure water flow, hot water if I can get it