Cleaned egr valve,no warning lights on,light puffs of blue smoke... not continues. Recent work performed,oil cooler replaced,egr valve,turbo replaced. 220,thousand

Blue smoke forms when the engine's lubricating oil is being burned, indicating worn piston rings, valve guides, or seals. Also, the oil can come from an overfilled crankcase. I only run full synthetic heavy duty diesel engine oil in trucks I service. Helps engine, EGR, and turbo, among other things, to perform and last much longer. Synthetic HDEO is crucial for turbo diesels.

The 6.0 was notorious for problems. EGR, head gaskets, so forth. I would recommend calling the dealer with your VIN and milage to see if there are any outstanding recalls for it. It may even have an extended warentee if no modifications have been made.