There is one other part that I am still curious about when it comes to the oil temperature. Inside the oil filter cover there are 3 valves. One is the drain valve which opens up when you remove the oil filter. The other 2 are in part of the same assembly. One valve allows the oil into the housing from the oil cooler and the other spring loaded valve is the oil cooler bypass valve. I've flow tested this valve but haven't done any real practice tests. IN THEORY if this valve hangs open or opens prematurely uncooled oil could enter the filter housing bypassing the oil cooler completely. No one has been able to determine a separate part number for this item so replacement is costly.
In the situation you are in, you may want to "tinker" with this valve or spring a little to see if you get a reduction in oil temperatures. Be careful though, because it's a relief valve keeping high pressure from compromising the oil side of the oil cooler so don't go too crazy.
The other thing you can try is take off the cover on the oil cooler housing which flows into the EGR cooler (or bypass tube), the one with the 2 screws then gently backflush the oil cooler directly. There's another member here who has had temporary relief when doing that.
Out of curiosity, do you have a coolant filter AND what coolant did you use? (nevermind, I just re-read your signature)
Now the good news for you. You don't have an EGR cooler so the 15 degree differential isn't a big deal so you can relax. Keep your oil temperatures reasonable (and I don't completely know what that is, so let's pick the number 235) and you're good. It would be great to see some actual data from manipulating that spring though!
Last edited by nylyon; 04-08-2011 at 05:13 AM.