METZCOOL wrote:
This is sign of plugged oil cooler.
Ditto. The wrench light will illuminate when the difference in temperature between oil and coolant exceeds fifteen degrees. The oil cooler clogs up, which starves the EGR cooler of coolant, which causes the EGR coolant to rupture, which causes coolant to enter the combustion cylinders, causing head gasket failure.
'Bulletproofing" the truck, which consists of head studs, new head gaskets, new oil cooler, and a redesigned EGR cooler is the answer to the problem. Talk to a reliable diesel shop about what it would cost. I did all that, plus some other goodies like a 4 inch exhaust and additional transmission filters for $5K.
Good luck. Once bulletproofed the truck should give you no further trouble.