6.4 Truck engine

[tron67j]

I didn't believe you so I had to go to RamTrucks dot com for myself.

What's even weirder is that it shows the "only option" (oxymoron if I ever saw one) for an engine is the Cummins, at a price tag of $9,695.

That is nutty. Wonder why they did that. It really crushes the ability to tow with it, a Limited with the diesel engine has around 2k of payload, subtract about 500 pounds for people, gear in truck and hitch, and using a 15% pin weight and the max trailer is about 10k pounds. Without anyone in the truck the maximum trailer would be about 13k pounds, well below the 19k " maximum towing " Ram lists for the truck I looked up.

You would have to be towing 2 axle hay trailers in a road train to use that maximum made-up number towing that Ram advertised.

 

[tron67j]

Not driven the 10 speed 2500 GMC but have spent some time in the 1500. Actually very nice. My opinion better than the 8 speed hemi 1500. ZF does not shop for gears as much but the GMC is eager and always in the right place. The older 6 speed 6.4 2500 has a bad wrap but drives well.

My 6 speed 2500 tows like a champ through mountains on East Coast and anywhere else I go. Don't want to start a discussion war here but would wager that problems can be sometimes associated with upper level GCWR and/or trying to do 75 all the time.

 

[Lsujker]

Figured I would give my 6.4 hemi experience. Purchased new and still currently own a 2017 ram tradesman with the hemi. Low miles at 55k. Truck has been great. Tow my jeeps few times a year. Random towing inclosed trailers and misc items. Most long drives include few times a year across states with my family. Fuel economy sucks and ride is harsh but drives well and has been reliable. Turn mds off every time. Would like to drive the 8 speed as they say it adds the performance missing but she paid off.

Issues with rear end locking up but salved with fluid change. Had an engine light misfire once at full throttle but all seams to be well. Great truck/motor combo. If I towed 7k more often or up and down mountains, no question I’m going diesel. 6.4 has to work at that weight but can do it. Temps run low so no worries. Not buying ford even with 7.3. Fords are num, squeaky, problematic and service here sucks. GM about the same and the interior is new but missed the mark. GM finally center the steering wheel with the seat. Kudos.

 

[HEMIMANN]

My 6 speed 2500 tows like a champ through mountains on East Coast and anywhere else I go. Don't want to start a discussion war here but would wager that problems can be sometimes associated with upper level GCWR and/or trying to do 75 all the time.

I wish I had more confidence in the 6 speed RFE transmission, in our case the 66RFE. All we know we learn from member experiences and those aren't statistically analyzed with the entire population of these in use.

Certainly getting rid of the trans oil cooler thermostat helps reduce heat-related oil deposits in the trans. Also using premium synthetic trans oil does the same. Keeping out of overdrive while towing, and using the tow shifting mode program to keep rpms up (out of low rpm shifting, gas-saving mode) are all known transmission longevity measures.

What we don't know is whether these are good enough to extend RFE trans life to 'expected' lifespan (200k miles, I would posit). We just.......don't know.

I'm a little less concerned about the Hemi engine since I switched oil to Red Line exclusively early on, and change every 5k miles. It's a proven tick reducer and killer. That actual data has been reported on here. But not RFE transmission life data.

 

[tron67j]

I have been reading about the red line use, 5w 30 I think, correct? I have only used PUP but do change every 5k, may switch to redline after I use up remaining oil.

For the transmission, I have read of problems here or there but without data it is hard to know where the problems are originating. For example if one puts big tires on the truck without upgrades to the transmission, etc. but still launches like a 10 second racer, one tends to have problems. Modifying the truck requires other upgrades or a change in one's driving habits. This is why I don't plan to worry; I will use the truck as it was designed and if I have a transmission failure then I rebuild it with better parts. In my years of driving with near a million miles under the belt I have replaced a transmission, flushed a few, rebuilt or replaced alternators and starters, and replaced a clutch among many fixes. It happens, mechanical things can break.

Could the transmissions have been built to handle more abuse, certainly but at a cost to everyone. I imagine there are millions of these transmissions out there and don't see evidence of millions of failures.

 

[Lsujker]

I have been reading about the red line use, 5w 30 I think, correct? I have only used PUP but do change every 5k, may switch to redline after I use up remaining oil.

For the transmission, I have read of problems here or there but without data it is hard to know where the problems are originating. For example if one puts big tires on the truck without upgrades to the transmission, etc. but still launches like a 10 second racer, one tends to have problems. Modifying the truck requires other upgrades or a change in one's driving habits. This is why I don't plan to worry; I will use the truck as it was designed and if I have a transmission failure then I rebuild it with better parts. In my years of driving with near a million miles under the belt I have replaced a transmission, flushed a few, rebuilt or replaced alternators and starters, and replaced a clutch among many fixes. It happens, mechanical things can break.

Could the transmissions have been built to handle more abuse, certainly but at a cost to everyone. I imagine there are millions of these transmissions out there and don't see evidence of millions of failures.

Would highly recommend not using 5w30 in the 6.4. Manual specifically states 0w40. Assuming Ram spec'ed a 0 weight oil at startup for a reason. But like you i stick with pensoil ultra every 5k miles. It will tick for 3 seconds on startup sometimes. So did almost all other modern vehicles I have owned.

My 6 speed runs at 169 deg. max when towing on 35" tall tires. If she goes, its not due to heat. The 1500 ZF runs 10 to 15 deg hotter with no load. Wonder what others have experienced.

 

[jejb]

That is nutty. Wonder why they did that.

Word was that 90% of the 2 Limited 2500's were ordered with the Cummins anyway. And Mopar/Steallantis has been trying to cut down on the number of options for years now. We ran into that when we got the wife's 21 Pacifica.

It really crushes the ability to tow with it, a Limited with the diesel engine has around 2k of payload, subtract about 500 pounds for people, gear in truck and hitch, and using a 15% pin weight and the max trailer is about 10k pounds. Without anyone in the truck the maximum trailer would be about 13k pounds, well below the 19k " maximum towing " Ram lists for the truck I looked up.

You would have to be towing 2 axle hay trailers in a road train to use that maximum made-up number towing that Ram advertised.

Yeah, that's the dirty little secret about 2500 CTD's, forced on us by the 10K limit the government puts on them. I knew that going in, but I also know I live within the legal limitations. The answer there, if you're going to haul heavy, is to get the 3500+.

 

[ramffml]

Would highly recommend not using 5w30 in the 6.4. Manual specifically states 0w40. Assuming Ram spec'ed a 0 weight oil at startup for a reason.

There is a 5 degree C difference in the spec between a 0w and a 5w. Yes, 5 degrees. 0w is good to -40C (-40F) and 5w is good to -35C (-31F).

What do you think is thicker. A 5w starting up in the summer at 68F, or a 0w starting up in the winter at -20F?

 

[HEMIMANN]

Perhaps he should read the 5,000 posts on Hemi engine tick in the Synthetic Oil Thread?

 

[Lsujker]

Perhaps he should read the 5,000 posts on Hemi engine tick in the Synthetic Oil Thread?

Why when you can explain it to me after my uninformed post?