6.4 Hemi - 8 Year Report

Irishthreeper

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Good to hear the longevity stories on the 6.4. My ‘21 2500 only has 17k miles, most of which were pulling our 5W, and I’ve been very happy with it. I wish
my ‘19 DT with 3.92 gears could have had the 6.4, the 5.7 alone was extremely quick. Using it for the HD’s makes sense though.
 

PCT

2019 2500 6.4
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Yeah, the guys saying how wonderful the 8 sp ZF trans is were getting to me, I'd love to get a 5th gen but except for the 66RFE I really love my 4th gen. And it's paid for.
Ive had my 6.4 for almost 3 years now, and just went past 25,000 miles (i was driving it ALOT until brandon F*#k gas prices) only put like 7k miles on last year... My Dart on the other hand i put 35k miles on last year lol. Anywho... The 8 speed with 4.10 is a monster. I drove my buddies 2020 6.4 with 3.73 and its mean but nothin like the 4.10's. Plus i get 16-18 MPG highway 70-75 cruise control, fairly flat, lifted on 35's. I am so far VERY happy with the 6.4. Sometimes i do wish i had the cummins for the sake of having a cummins, but overall 6.4 with the 8spd is a mean combo.

Side note, i think TFL did a disservice to the truck using the 6.4 with the 3.73 and not 4.10 and it not being broken in. It took my truck a solid 2 oil changes (7-10k miles) to really open up.
 

wyo2track

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2014 RAM 2500
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6.4L Hemi w/ 4.10's
81k on my 2014. Engine is strong. Wish I had the 8 spd but have not had any issues with the 6 spd some have had but many have not. After reading this thread think I'll be changing my transmission oil to the Amsoil...good info. Have had a few hiccups; clutch fan under warranty and the one that's on there now acts up now and then. Out of warranty, out of pocket; rear u joint, cracked radiator and failed thermostat, rear view camera and an electric window motor. About $1500 out of pocket so far in the 8 years. Lots of dirt roads in my area the truck has seen. Local shops haven't seen the engine or transmission problems on YouTube and forums.
Should sell it now since prices are so hi, but keep hoping RAM updates the HD cab before doing that. Interested in the Ford 7.3L as it has that 10 spd, more torque, and has a bigger cab, but it doesn't do any better mpg unloaded than what I have now. Drove a friends new F350 with 7.3, 3.73's and 10 speed and it is strong, but maybe I'm to the point of springing for a tuner to shake things up. Haven't had to make a payment on it in the last 4.5 years so I think I'll just keep on putting miles on it.
 

HEMIMANN

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81k on my 2014. Engine is strong. Wish I had the 8 spd but have not had any issues with the 6 spd some have had but many have not. After reading this thread think I'll be changing my transmission oil to the Amsoil...good info. Have had a few hiccups; clutch fan under warranty and the one that's on there now acts up now and then. Out of warranty, out of pocket; rear u joint, cracked radiator and failed thermostat, rear view camera and an electric window motor. About $1500 out of pocket so far in the 8 years. Lots of dirt roads in my area the truck has seen. Local shops haven't seen the engine or transmission problems on YouTube and forums.
Should sell it now since prices are so hi, but keep hoping RAM updates the HD cab before doing that. Interested in the Ford 7.3L as it has that 10 spd, more torque, and has a bigger cab, but it doesn't do any better mpg unloaded than what I have now. Drove a friends new F350 with 7.3, 3.73's and 10 speed and it is strong, but maybe I'm to the point of springing for a tuner to shake things up. Haven't had to make a payment on it in the last 4.5 years so I think I'll just keep on putting miles on it.

You can use Red Line +C ATF with your 6 sp trans also. It's only with the 8sp trans users have reported slippage, fyi.
I plan to use Red Line @ next change because polyol ester in base oil is unsurpassed in thermal stability. It is jet engine oil. Even beats Amsoil's PAO base oil. Then again, it's $18.95 a quart, so there's expense. But - trans oil isn't changed every 5,000 miles like an engine, and my trans only changed out 7 quarts. So why not go with the best in our marginal RFE transmission.
 

wyo2track

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6.4L Hemi w/ 4.10's
You can use Red Line +C ATF with your 6 sp trans also. It's only with the 8sp trans users have reported slippage, fyi.
I plan to use Red Line @ next change because polyol ester in base oil is unsurpassed in thermal stability. It is jet engine oil. Even beats Amsoil's PAO base oil. Then again, it's $18.95 a quart, so there's expense. But - trans oil isn't changed every 5,000 miles like an engine, and my trans only changed out 7 quarts. So why not go with the best in our marginal RFE transmission.
Appreciate the information you provided as well at the OCI regarding temp stability. I haven't changed the transmission oil so I'm probably due. Most the time I never see engine oil temps above 205F unless I'm working it, but that's only 15% of its life. Heck, during colder months, Nov. - March, I hardly see 200F engine temps. This 6.4L has 3 efficiency modes when unloaded and there all ambient temp related...lol. Below 35F, oil is 185-195 and sucks gas. 35-50F, might get 200F on the engine and it loosens up a bit. Above 50F is the best by far. Is there any other threads on the pulsar tuner you're running? I know with this 2014 I could still go the custom route without a new pcm, just haven't.
 

HEMIMANN

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Appreciate the information you provided as well at the OCI regarding temp stability. I haven't changed the transmission oil so I'm probably due. Most the time I never see engine oil temps above 205F unless I'm working it, but that's only 15% of its life. Heck, during colder months, Nov. - March, I hardly see 200F engine temps. This 6.4L has 3 efficiency modes when unloaded and there all ambient temp related...lol. Below 35F, oil is 185-195 and sucks gas. 35-50F, might get 200F on the engine and it loosens up a bit. Above 50F is the best by far. Is there any other threads on the pulsar tuner you're running? I know with this 2014 I could still go the custom route without a new pcm, just haven't.

Trans oil temp is different in that we don't expect to change trans oil every 5,000 miles like we do with engine oil (do to blowby contamination). Therefore, we don't worry much about oxidation life of engine oil - but it is absolutely critical with transmission oils. Many members get rid of the dumb trans oil cooler thermostat to get their oil temps back down to where they've always been since auto trans were first introduced. If you run 200F trans oil, you need to change oil every 10,000 miles. At least.
 

BLUKTY2

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Interesting thread and figured that I would chime in. My 2017 6.4 3500 with the 6 speed trans is just now approaching 50,000 miles and I have been very happy with this truck. Bought it new so I know all of its maintenance history. Really the biggest issues that I have had with it are the recalls, especially the drag link recall. Initially I got the welded jamb nuts "fix" but after I insisted to Ram Cares that this "fix" was completely unacceptable, I now have the updated drag link installed.

About 18 months ago I got a repeated misfire code on cylinder #3. Each time I cleared the code it would come back within a couple of days or so. The engine always ran great during these episodes so I was sure it was just a "phantom" misfire code. At any rate, I ran a bottle of STP Fuel Injector cleaner through one tank of gas and haven't had a misfire code since. Coincidence? Perhaps, but the bottom line is no more CEL's or codes.

Other than these minor issues, I have had no problems whatsoever. And this truck works HARD; it carries a heavy camper (about 3,800#'s) 98% of the time on the mountainous and not-so-perfect roads of Alaska, sometimes towing a light trailer (1,600 #'s). It is not my daily driver so a vast majority of its miles are highway miles.

I am running Amsoil in the engine, transfer case and front and rear differentials. I never push the engine OCI and only once exceeded 5,000 miles. Most of the time I don't exceed around 4,500. Am I throwing some money away using this interval? I'm sure that I am. Do I care? Absolutely not! As has been pointed out in this forum, oil is a lot cheaper than engine parts.

Front and rear diff oil were changed at around 16,000 along with the transfer case using OEM fluids. Then again at around 40,000 with Amsoil. I figure that these fluids are good for quite some time. I had the trans serviced at around 30,000 and OEM fluid was used as I had this service done at the dealer. Will have it changed again when I get closer to 60,000.

I changed the brake fluid at 3 years (2020) and plan on changing it again within the next few weeks.

In summary, the truck drives great, has plenty of power, the cab is very comfortable, and so far has been very reliable and trouble free. No regrets with this purchase whatsoever.
 

Omegasupreme

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I have a 2018 with 128k now. No issues with trans or engine. Except exhaust manifolds keep warping. I wish the 6.4 had 50 more torques under the hood. I tow a big dump trailer every now and then, and 5 yards of dirt it really struggles.
Overall, for the price of new, you can't beat it.
 

HEMIMANN

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6.4 Hemi with heavy loads (10-12k lb trailers) needs either the 8 speed ZF trans, or earlier models with 6 speed RFE trans, the 4.10 gear ratio axle.

I have the 6 speed 66RFE trans, truck came with 3.73 gear ratio axle. I only pull 7 pound trailer max. Anything higher and I'd change the gears out.

My dealer tells me to plan for dirt weight @ 1 ton per cubic yard, so you're talking 5 tons (10,000 lbs) of load PLUS the trailer weight. Guessing you're near the GTWR of 12,000 lbs. Using the gas motor at this max load means adhering to the powertrains I listed, at minimum. Tuner helps too.
 
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