6.4 powerstroke rebuild.
 

So my 6.4 has been acting up here recently. Oil temperature is out the top and when I say that I saw 285 today on my h&s display. I had the same problem a month ago and thought it was the oil cooler so I had it replaced it and it solved the problem (coolant and oil temperature were about 5-10 degrees apart which is normal) until a week ago . The truck is a 2008 f450 but has a regular bed and has all the deletes with a h&s mini max and has 157k miles. I run the truck on the stock setting because a tow heavy with it all the time around 25k sometimes more. The mechanic I took it too did a test and told me the head gaskets were ok. They flushed the coolant system before they installed the new oil cooler. I still think I have a blown hg so my mechanic said to bring it back in and he will check everything again. It does push a little coolant out the degas bottle but not much maybe a quart. Is there something else that could be causing that high of oil temperature? Coolant temp runs anywhere from 190-215 oil temperature usually 50 degrees above that sometimes more. If it is the hg or cracked head what all should I change out/ replace while I have it apart that far? I have the money to repair it but not the money for a new truck.