When I first got this 2006 F350 with the 6.0 engine, I seriously considered just posting it on Craigslist and selling it because of the things I'd heard and read about on the engine, but the body and interior was in such good shape, I reconsidered.
I talked to several people who who had a lot of knowledge about them and for the most part the consensus was if it was running well at the start to flush the cooling system to make sure none of the Ford coolant was in it and to remove any casting sands that might still be present. Then they all advised to put a coolant filtration system on it and do annual filter changes there. The second thing was to beef up the battery and alternator wiring, along with a larger amp alternator to prevent and electrical damage to the electronic components and to change out the fuel pressure regulator spring with the new improved kit. Then, make sure the EGR was deleted, since a failure in that system could crash the rest of the engine.
The next item was to install gauges or have a monitor to keep an eye on critical components, just in case. I went with an Android app that cost $5.95, used an old cell phone and bought the OBDII bluetooth transmitter for $18.00.
Info from the internet strongly advised changing engine oil at 5K intervals instead of 7.5K, so since that tracked on the point where I change the oil in all my vehicles, I followed that.
The Ford techs all advised against any kind of tune that affected the Powertrain Control Module, telling me that they could ruin a transmission or increase cylinder compression, which would lead to cylinder head or gasket failure. I went for a 45 HP tune that only affected the Fuel Injection Control Module - which makes this truck drive like a gas engine on take offs.
Since then, I've used it pretty much as a daily driver, many, many short trips, but I take it out once a week and get it good and warm, then drive it like I stole it for a few miles, exercising the turbo.
Then several times a year, I'll hook up the 11K fifth wheel and head out, pulling as much as 700 miles one way.
The truck has never approached any critical points in the areas I monitor with the phone, I've never had a problem with it, and the only thing I've had fail is one glow plug. I''d really like to get a Ford with the 6.7, but I simply cannot justify that kind of expense, so I'll keep maintaining this old beauty. With the way it's running right now, it's probably the last truck I'll ever own and I sincerely believe that the engine is capable of at least 350K miles, but I doubt that I'll be driving it when it does hit that point.
This is just my experience with the 6.0, many disagree with me, but to each his own. I would point out that prior to this truck, I was a diehard GM truck fan and several friends have reminded me of all the jokes about Ford trucks I used to tell them back in those days.