Need advice please

As mentioned, make/model really makes no difference, I know what I prefer, and that's what would matter for me.
The DOT inspection is a biggie, as well as an oil analyses, that can tell you a lot, as well as service records. Mileage? I've had trucks with 1.7 million on them, and I've had new ones, and both were dependable. I wouldn't be afraid of a truck with over 600k on it, as long as the service records were there and the oil test came back good. Then drive it, it's not that difficult to tell if there are driveline problems, tire problems etc.
Right now, I've driving a T8 heavy hauler with just under 700k, I actually prefer it over the 4900SA Star Car that is the other truck I drive, both have the same specs, The Star Car only has 110k on it, and no where near the dependability, engine wise.

 

What do they look for in an oil analysis test, johnday?

 

they look for different metals and particles in the used oil the amounts of them indicate the condition of the internal components of the motor. they also check for antifreeze and fuel that have made there way into the oil, different types of metals indicate any abnormal wear on different components

 

Wear metals, carbon build up, anti-freeze, diesel fuel, contaminants. .....


Some guy's I know will go 100,000 miles on oil so long as the analysis comes back as good as bottle of new stuff. Of course anyone selling a truck could change the oil and hide major metal counts and such because the buyer would have no point of reference to know how old the oil was/is.

 

Ezrider and Tazz are right, sorry, I had to go to work and didn't see this. Yes the owner could try to pull a fast one and have fresh oil in there, but the analyses would still show some bad stuff if it was in there, not as much as old oil, but would still show. There would be residual oil in the engine even with an oil change, you just can't get it all out. That's the way it was explained to me.
May be someone can give you a lab to call and ask them, it's been at least 10 years since I've had one done, and can't remember the name of the lab I used.
I am getting old! LOL

 

http://www.blackstone-labs.com/free-test-kits.php