6.7 Cummins HPL or Amsoil

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Jul 5, 2026
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Hi, first time posting but I've been reading trying to learn for a few years. I have 3 Rams with the 6.7 Cummins, 2 with hydraulic lifters and one with flat tappet. A 15 with 470k miles, 21 with 310k miles and just got my new 26.
I've tried a few oils on the hydraulic lifter engines, VPBE, Delvac ESP and Amsoil HD, all in 5w40 since trucks pull over 30k lbs so gross right around 45k lbs, out of those 3 truck seems to like Amsoil the best, quieter starts and runs smoother over the life of the oil, I know that might sound anecdotal but I've driven close to a million miles on my Rams so far so I'm pretty good about noticing changes on them. Oil gets charged whenever the computer says, I've sent some samples for analysis to make sure and they all come back looking good saying I could go even longer bit I just wanted to make sure that by changing it at 12k miles when computer says I wasn't damaging the truck.
My question is would I gain anything by going from the regular Amsoil HD to let's say their signature series or HPL PCMO? I know HPL is the favored oil here and I don't mind spending the money since truck being down cost a lot more than a few dollars in maintenance.
My research here seems the order would be HPL premium>Amsoil signature>HPL PCMO>Amsoil HD, is that correct?

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The only way to really know how they would do is to run 'em and take several UOAs. Then see how your choices hold up, and rate them against some ROI criteria.

BTW - the "PCMO" isn't for diesels. So perhaps choose a different HPL product; something from their CK series.
 
The only way to really know how they would do is to run 'em and take several UOAs. Then see how your choices hold up, and rate them against some ROI criteria.

BTW - the "PCMO" isn't for diesels. So perhaps choose a different HPL product; something from their CK series.
Sorry, I thought that what he called it, it's the HPL HD I was thinking about. Reading it seems that HPL would be one of the cleanest running oils correct?
 
HPL 5w40 HTHS is 3.9 vs 4.2 for Amsoil, would that make any difference on protection? Some of the grades I do truck will show oil temps in the 240s F° since I'm in Phoenix
 
HPL 5w40 HTHS is 3.9 vs 4.2 for Amsoil, would that make any difference on protection? Some of the grades I do truck will show oil temps in the 240s F° since I'm in Phoenix
Might want to message Dave himself at HPL he is best to answer and what is best grade to run .
I have run the HPL premium in a 21 HO in Phoenix for a few years without issues ever.
Just curious what filter are you using.
 
Don't get me wrong—I use HPL in one of my vehicles, as well as in my generators and mower, and I think it's an excellent oil. I also have a high opinion of Amsoil. That said, I run Chevron Delo XSP 400 5W40 in my 6.7 Cummins because it has a 4.2 HTHS and comes in at a lower cost. There's absolutely nothing wrong with running HPL or Amsoil; this is simply the option that makes the most sense for my application.
 
Might want to message Dave himself at HPL he is best to answer and what is best grade to run .
I have run the HPL premium in a 21 HO in Phoenix for a few years without issues ever.
Just curious what filter are you using.
All I've ever run is the Donaldson blue DBL7349 filters but the new 26 runs a cartridge filter so I'll have to run fleetguard for now.
I talked to him last week, he recommended 5w40 also, will be running that on my 19 3500 that pulls the boat after doing his engine cleaner since that one uses a little more oil than the other trucks.
For the 5500 I'm leaning towards the Amsoil with the higher HTHS since that truck pulls 30-35k 100% of the time
 
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Don't get me wrong—I use HPL in one of my vehicles, as well as in my generators and mower, and I think it's an excellent oil. I also have a high opinion of Amsoil. That said, I run Chevron Delo XSP 400 5W40 in my 6.7 Cummins because it has a 4.2 HTHS and comes in at a lower cost. There's absolutely nothing wrong with running HPL or Amsoil; this is simply the option that makes the most sense for my application.
I haven't tried Delo XSP yet but here at Walmart it's $40 a gallon so that puts me into Amsoil/HPL price
 
I haven't tried Delo XSP yet but here at Walmart it's $40 a gallon so that puts me into Amsoil/HPL price
I just picked some up for $34.99/gal from O’Reilly. Although I did have a stash I bought from AAP on clearance for $8.99 a gallon a while back, I’ve since used all of that. I was going to go back to VPBE from Napa, but it’s no longer 25/gal like it used to be. Just keep an eye out for sales if this is something you’re interested in using.
 
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All I've ever run is the Donaldson blue DBL7349 filters but the new 26 runs a cartridge filter so I'll have to run fleetguard for now.
I talked to him last week, he recommended 5w40 also, will be running that on my 19 3500 that pulls the boat after doing his engine cleaner since that one uses a little more oil than the other trucks.
For the 5500 I'm leaning towards the Amsoil with the higher HTHS since that truck pulls 30-35k 100% of the time
I've always ran the DBL7349 also with good results.
 
Don't get me wrong—I use HPL in one of my vehicles, as well as in my generators and mower, and I think it's an excellent oil. I also have a high opinion of Amsoil. That said, I run Chevron Delo XSP 400 5W40 in my 6.7 Cummins because it has a 4.2 HTHS and comes in at a lower cost. There's absolutely nothing wrong with running HPL or Amsoil; this is simply the option that makes the most sense for my application.
Yes any ‘ol proper spec oil will do just fine in the OP’s situation.
 
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