Engine Hrs (mph)… how important?

[KeystoneFlyer]

In my quest for a relatively lower mileage 06-07 PSD, I consider as much historical info about a truck that I can find: owner/dealer comments, OASIS, service records, usage, location (road salt), etc. etc, and of course engine MPH (idle time)! I understand that 30 MPH seems to be the generally accepted minimum (more the better, i.e. less idle time). Some of the trucks I am looking at have 32-43k miles/35 – 40 MPH (good), and a few have 14-17k miles but have 24-26 MPH engines (not so good). So, should I always pass on the higher MPH/idle time trucks (less than 30 MPH)? or would you still consider a very low mile truck (14-17k with a 24-26 MPH engine) given that the TOTAL engine time/wear on the low mileage truck may in fact be less than a truck with 32- 43k/35-40 MPH ? Heck, what about the 32-37k/24-26MPH truck? Thanks folks for your opinions! (For the MODS, if this belongs in the 6.0 forum, by all means, move/re-post.)

[colo_dually]

The higher the idle time, the longer that motor has been running without a proper load applied to it, and its an artificial mileage when you start talking an average 26 mph, compared to engine hours.

Diesels are not really intended to run at idle for extended periods of time and remain in good working order. One thing is the additional carbon build up in the intake and EGR systems of these trucks which lead to issues. The turbos do not get cycled properly to help prevent sticking. All of which cause issues with the 6.0L, it has to get worked under a load or WOT continuously to work correctly.

The biggest thing to look at if on the high-idle truck would be to see if the maintenance was done to the truck per the heavy service guidance (exp: Oil every 5K miles/XX engine hours, I don't have the manual with me so I'll try to get the hours later). If they followed that, you should be ok. But I would look the truck over very closely.