Hello John.
I can't comment on the Pete/Cummins combonation, but I can throw in my 2 cents about the Western Stars.
The company I work for replaced our fleet of aging KW T800 tridrives in 2015 with a fleet of Westernstar Tridrives,
Ours are equipped with the DD16 EPA10/GHG14 engines, Eaton MXP 18 sp Ultrashifts and the Neway ADZ suspension.
We don't "haul" on the hiway. The trucks only hit the pavement to go back and forth to the shop and depending on the haul, if they can run empty up the hiway to go back for another load, they will.
Needless to say, they will run MAX gvw just about every load.
Going from the old KW's with a stick and Cumins ISX in them to the DD and the self shifting trany's has been interesting.
So with 13 trucks running, we work 7 days a week, we now have over 2 million Kilometers on the fleet. Hard kilometers as logging will do to trucks.
I am the guy that runs the shop at night, so these things are my girls. I have gotten pretty intimate with them.
NOT a fan of the ADZ. When the trucks were spec'd out, there must have been a bean counter involved ( I like to call them Ink Maggots) and they saw that if we went with the ADZ we could up our GVW by a few pounds. We have had lots of grief with them. Our logging roads are not the best, we run on steep ground, switch backs coming off mountains and such.
There is not enough movement allowed with this system for our application. We have to really keep and eye on the components and change them out early to avoid catastrophic failures. Most of the fleet has been back to the dealer for some warranty upgrades on this system.
The Ultrashifts have been interesting. The drivers are about 50/50 on how they feel about them. They don't like them during the summer when we are up in the mountains, if you slow down too much and the trans downshifts, you are not ever going to get back up to speed. The inclinometer built into the system will not allow the trans to upshift. Dumb. The drivers have learned a few tricks to get past this.
They also don't like them during periods of snow and slippery conditions. You might want a higher gear to avoid slippage and trans will not allow.
Other times of the year, they love it. I have had more then one guy tell me that they go home at night feeling no where near as tired as they did after scrambling eggs all day with a stick.
Just a note here, the old KW's were all 18 speed manuals, so they were all used to driving sticks.
The old 18 speeds that we ran were a damn fine trans. We had a few drivers that abused them, but that is what happens with fleet. I would not hesitate to spec one out in a truck again.
Now for the engine.
So far, touch wood, we have not had any major issues. With 13 trucks, there has been a few warranty issues but nothing serious.
Things are just starting to show up now, but like I said at the start, they are 2 years old now and hard miles.
WE had one truck that had an oil pressure issue, it turned out that it had the wrong engine oil dip stick installed at the factory. The dealer covered that one no problem.
We are finally starting to have issues with the emission part of the system. The "One Box"
I have a laptop with the DD program in it so I am able to do most of the diagnosing and repairs. Temp senders and NOx sensors. The temp senders are about $100 and the NOx are around 4-500 if I remember correctly. So with the 13 trucks I think I am at about 4 NOx sensors and 6 Temp sensors. Not to bad since there are 13 (I think it is 13) sensors in each one box.
What I have had to change out quite often is the DEF harness that runs from the truck to the DEF tank and pump. The mud and crud off the steer tires get thrown all over the harness and it sits inside the loom and it acts like grinding compound and eats its way through the tiny little wires. It is a $90 dollar harness, takes about a hour to change out.
Right now I have one at the dealer. Problem with the DEF system. I think it might be contamination, but I do not have the proper stuff to test the DEF with so I sent it to the "experts"
Other "learning" problems that we have had.
During the winter months, we can be on a short haul.
The emission system has certain parameters that it need to meet to initiate a passive or active regeneration.
So the truck will ask for a parked regeneration. (A DPF burn)
The drivers were trying to skip doing a parked burn, ( possibly because the foremen were leaning on them to get the loads)
Ignoring this is a bad thing, as we found out.
A parked regeneration will take 30 to 60 min depending how plugged things are. DO NOT IGNORE IF CALLED FOR
We had to replace a one box because of a driver ignoring the code.
There might have been a warranty issue going on also, cant remember.
The drivers like the engines. LOTS of power.
I'm not sure what the fuel consumption is, but you cannot compare what we do with highway miles.
Now onto the truck.
Our biggest problem to date with the truck itself.
The radiators.
Can NOT keep them from leaking.
The stock rads are JUNK, Modine garbage (Just a personal thought here).
The dealer has resealed or changed out every rad at least twice.
They keep using the same garbage.
We have a spare rad and have sent it to a radiator repair shop that is used to dealing with trucks that haul on crappy roads like ours. The install a heavy duty industrial core with better gaskets. So far they have been doing the trick.
Westernstar also has the hood mounted so that it is on the radiator mount. With our horrible roads, the extra weight of the hood on the rad mount beats the hell out of the rad mounts. Dumb.
We also have lots of issues with cab mounts. They look like they melt. I think it is just the friction from the cab shaking all day on the dirt roads.
And the wiring.
We are alway repairing the wiring for the headlight and the turn signals on the hood, driving and fog lights. Just horrible wiring.
But once again, rough dirt roads.
So to sum it all up
These trucks are spec's heavy haul.
We haul heavy on dirt roads.
If you were using these trucks in a Highway application, most of the problems that I experience will probably go away. The pounded out rad mounts, the rad problem themselfs, the cab mount, the worn out wires.
Feel free to PM me if you want anymore information