Check your coolant level. If low, pull the EGR valve and look for moisture after the truck has cooled. Also look at the right side exhaust manifold where the up pipe connects and inspect for evidence of coolant leaking. These things will point to a failing EGR cooler. After shut down clooant leaks into the cooler and runs back down the right up pipe where the cooler is connected to. Head gaskets will not cause your symptoms. The fluid in your exhaust pipe is most likely coolant mixed with the carbon in the exhaust giving it the appearance of oil - a common incorrect identification of the fluid. Oil would only make it that far if the turbocharger seal or bearing completely failed and was dumping oil into the downpipe and you would have extreme smoke that will not clear up. The EGR cooler is your most likely bet. Good Luck!
