Scan gage numbers

In general, you do not want the delta (difference) between engine oil temperature and engine coolant temperature to exceed fifteen degrees beyond very short periods. If the no load difference exceeds fifteen degrees consistently, you are probably looking at a clogged oil cooler, clogged EGR cooler, or both. If you do not have a coolant filer installed, do so. There is a lot of loose casting sand in those engines and it can lead to clogged coolers. The coolant filter kit can be had for about $130.

Bulletproofing with a revised EGR cooler, head studs, and new oil cooler will bring your engine back to good performance if things start to go south.