I owned 3 6.2s. All of them lasted 300k+ and got 22mpg plus. Just because you had problems doesn't mean they are bad. The 6.5 issues could have easily been rectified but GM chose to ignore it. Atleast the blocks didn't fail like the late 80s 7.3s . You should really get you history straight. The 6.2 is not what gave GM a bad rap for diesel tech, it was the 5.7 handgrenade. The 6.2 was a good engine but after the mess with the 5.7s alot of people were turned off to them. Most 6.5s that ar taken care of last close to 300K. I have 2 both with 171k.
This true of any engine if the PO beat the heck out of it and towed Goose neck trailers witch i just discovered the hole in my box by the way were such a hitching device was once located then its going to the be a beaten rig. . .
Alot of people don't take care of there Trucks as the owners manual says too !
Did you know the owners manual in my truck says to change the oil every 2,500 miles ? I wonder how many 6.5 owners do that ?
the manual also clearly states DO NOT use OD for Carrying heavy loads towing trailers while operating on steep hills or when off road. How many 6.5 owners you guess do all of them things in OD ?
Follow the manual and about every engine out would last much longer then it dose. . .
the 6.2/6.5 do not make the amount of power the 5.9 and 7.3 do of the same model years, now that being said the 7.3 n 5.9 both came from 16K-36K-LB GVWR truck's that tended to get used for 300K-500K miles, as were the 6.2/6.5's GVWR's were 6K-9K-LB's, not saying they wern't used in truck as heavy as 14K-16K, but didn't seem them in trucks like C40's-C80's such as the other 2 engines were used.
6.2/6.5 bad engine's more then likely not, they are light duty app Motor's that got over loaded over worked and under maintained ! Tho I'm sure PMD failures getting misdiagnosed as Injector pump failures at $1,500-$2,500 a hit didn't help them much either. . .
I personally think the 6.2 was a little more dependable then the 6.5 due its lack of electronics . . .
I to have seen with my own 2 or rather 4 eye's 2 6.5-T's with over 300K miles still getting used 1 with 327K and the other with 393k, But the Driver of them 2 trucks also dosen't run them during the winter months any more as around 150-170K miles the both wouldn't start once temps tipped into the 20's. . .
which seem to be about where mine is now at 135k miles. . .