We have an 08 6.4, bought new in August 2008. We currently have 65k on the truck. I am currently monitoring and concerned about high metal content in my motor oil in the last 4 Blacksstone oil reports. It prompted me to purchase the extended warranty out to 96k (3 more years).
Since August 08, we have had the following problems.
@ 3k miles when towing, lost turbo pressure, but returned, dealer was unable to identify cause.
@ 16k, lost turbo pressure again when towing, dealer claimed hose clamp loose.
@ 20k, lost turbo pressure (not towing), dealer finally identified wiring harness shorted against hot exhaust.
@ 40k, rear camera stopped working, Camera replaced.
@ 46k, fuel/water separator drain lever broke, replaced.
@ 50k, fuel/water separator drain leaking, replaced.
@ 60k, replaced 4 tires
@ 62k, replaced shocks
The truck has otherwise been good to us. I love the power and I get about better fuel mileage than most. We get 19-20 on highway trips and average 16.5 during normal mix driving (empty). Yes, this is hand calculated. The maintenance on a diesel truck was a bit more painful than I expected. You have to really stay up on the maintenance and oil changes are pricey. When things break they are EXPENSIVE. The regens are a pain in the rear, they always occur at the worst possible time and Ford's most recent PCM flash removed the warning.
All that said, I would buy another Ford Diesel, 6.7 or 6.4. Based on the research I have done on other brand's modern diesel engines, they are all prone to high pressure fuel pump failures, EGR problems, and other issues. None of the modern engines are as reliable as the Cummings 5.9 or Ford 7.3, but then again they don't have the power nor are they as clean (emissions).
My advice....
If you plan on driving short daily trips, buy the gas. The new diesels do not do well with short trips.
If you don't plan on making a lot of RV towing trips, go with a gas engine. If you do plan on making a lot of long distance trips, the diesel would probably be better. You will have to compare the fuel economy and determine if there is a cost advantage to the diesel.
If you are buying a used diesel, get oil samples, check the maintenance history and if possible, get a warranty. If no warranty is available, make sure the price makes it worth the risk.
Good luck,
OJ