Got an 05 6.0. I have 68,000 on it and just had it in the shop for a minor oil leak at the turbo. Under warranty, cost me $100 bucks (deductible). I have a programmer (superchips) that I run with the fuel economy setting. I really don't see that big of a difference in mpg with it or without it and have been meaning to return it to stock for the last 6 months, just keep forgetting. I will say that it will friggin' carry the mail in the performance setting. I've heard tons of horror stories about the 04 6.0's but seems like they worked a lot of the bugs out of the 05 and newer 6.0's. Probably more dudes on here that can speak more knowledgable about it than I can. But, I haven't had any issues (other than the oil leak) since I bought it new in May 05.
Talked to the service guy at the dealer the other day (who owns a 7.3 with 275K on it) and he said he wouldn't own an 04-08 or any 6.0 for that fact. He said the 09 and 10's (specifically the 6.4L) SHOULD be ok but he's seen some of them with problems. He seemed pretty surprised when I told him that I hadn't had one issue with my other than this oil leak.
I know you weren't asking about anything newer than an 05 BUT...
he also mentioned that the 08-10's are getting awful mpg. Too the point that they had tons of customers across the country bringing them in asking them to fix them (most were getting less than 10 mpg's with the a few getting 12 at best that he'd seen). He said if you were considering a new one, hold out for the 11-12's in the 6.8L (I think...could have said 6.7L...new motor built by Ford...the 6.4 was contracted out (don't know by who). "Estimated" mpg of 19-21 on the hwy. I would have to see it to believe it.
There is also a new additive that will be required on all 10's rolling off the line this year. It is (I think) an 8 gal reservoir that holds some type of liquid friggin' gold that costs $8/gal. It is a new emission additive that is required by a new federal law on all diesels built after May 2010. Will require a change with every regularly scheduled oil change. Do the math on that one...
Hold on to your old diesels boys, they're appreciating as we type...
And concur with you Owen. Hold out and find you a good ole 7.3 or a 05 or later 6.0 that hasn't had one issue and has more than 75K on it. Going to be tough to find though. Folks just ain't getting rid of them.
