5W40 or 15W40 in 6.7 CTD?

[BurbMan]

So the owner's manual in my 2015 Ram says to use 15W40 oil in the 6.7 Cummins diesel, unless the temp is going to routinely be below 0*, in which case you should use 5W40.

Here on Long Island, the temp rarely if ever even gets to 0*, much less stays under it for any period of time. I'm coming up on my first oil change since I've owned the truck, and I was all set to stay with 15W40. However, guys on a couple forums are saying they use 5W40 year round.

Please let's not get into a brand war or discussion about dino vs. synthetic, but I'm interested to know what weight oil you guys are using.

[Cummins12V98]

rhagfo wrote:

blofgren wrote:

rhagfo wrote:

otrfun wrote:
If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

Well even if it is a bit more I like to be constant with the oil I put in my engines, and like it to be good quality.
This is part of the reason why, this is the tappet gallery on our 2001 Ram CTD at 300,000 miles.

Wow, that looks great! I only use top quality oil as well along with OEM filters in all of my vehicles.

I order my filters from Geno's Garage, yea they take a week to get here, but I order replacements when I use the ones I have, just in case I get some bad fuel.

You may have said but that looks like you ran Delongs 400 with all the black streaks.

I did my killer dowel pin at 100k on my 98 12V pulling front cover. My truck was Delongs for the first 50k when I bought it I switched to AMZ/OIL 15-40 Diesel Marine. Did the same on my Dad's 94 12V at 120k, he used the AMZ/OIL after first change. My engine was clean but had a lot of black streaks on the front and under the valve covers. My Dads was a golden spotless clean on both locations.

Does it matter??? Who knows.

[ShinerBock]

FishOnOne wrote:

For '19-'20 6.7 Cummins with the hydraulic lifters require 10W30 or 5W40 oils and have moved away from 15W40 oils. Some who have ran 15W40 in these trucks have reported rattling or knocking noises.

I haven't heard about knocking or rattling noises on a new 6.7L due to using 15w40. Although, it would have to be pretty pronounced since the 6.7L is a fairly loud engine and 15w40 has the same viscosity grade as 5w40 at operating temp.

Most engine manufacturers are going to lighter engine oils due to fuel economy concerns. The hydronic lifters may have something to do with as well, but the main reasons for this shift is likely due to the upcoming CAFE fuel economy standards that include all classes into the average instead of just class 1-2A. Every little bit counts and even small gains with keep them from paying millions in fines.

[Grit_dog]

Fish, Shiner, don’t fall into the consummate antagonist trap like a lot of the members here.
The UPS example is plain and simple and example of it doesn’t matter if you overchange and run boutique oils.
And the 300k example is just that. 300k, looks pretty clean, runs good and all that on “cheap” oil.
Cmon guys. Give a little credit where due once in a while. I know you’re a couple of the sharper guys on here.

[FishOnOne]

rhagfo wrote:

blofgren wrote:

rhagfo wrote:

otrfun wrote:
If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

Well even if it is a bit more I like to be constant with the oil I put in my engines, and like it to be good quality.
This is part of the reason why, this is the tappet gallery on our 2001 Ram CTD at 300,000 miles.

Wow, that looks great! I only use top quality oil as well along with OEM filters in all of my vehicles.

I order my filters from Geno's Garage, yea they take a week to get here, but I order replacements when I use the ones I have, just in case I get some bad fuel.

Not sure Delo is performing exceptional here with the black residue build up on the push rods. Can only imagine that black build up behind the ring lands.

[FishOnOne]

ShinerBock wrote:

mr61impala wrote:
Let me preface this by saying this is NOT a recommendation.

I recently retired from UPS in the Automotive department, 9 years as a diesel mechanic and the rest of my career managing the shops.

UPS has the largest privately owned fleet of vehicles in the world so cost is a huge factor, I am going to tell you something you will not believe but trust me, it's true.

Around 20010, in an effort to reduce costs and after discussions with the various suppliers, UPS decided to use 10w30 exclusively in all delivery vehicles. Cummins was one of our suppliers who signed off on this decision.

We have been running 10w30 in all 5.9 and 6.7L Cummins, with a 15,000 oil drain interval since that time with no ill effects. Read that again. Most 6.7L engines exceed 500K miles with only water pump, turbo, injector, EGR valve and maybe EGR cooler replacement. I know of one in particular with over 600k miles that still only consumes 2 qts of 10w30 between those 15,000 mile oil changes.

The primary cause of CTD failure is injector failure, stripping the cylinder walls of lubricant. If it starts missing or smoking SHUT IT OFF until the cause is corrected.

Again this is not a recommendation, just interesting results of a huge real world reality.

This is kind of apples and oranges in terms of use. The reason why Cummins signed off on 10w30 for your trucks and many other applications likes it is due your constant stop/starts. Constant stop/starts is not good on many engine parts and adds a lot of wear to cylinder sleeves. Oil recommendations are generally based on applications and a UPS truck application is not the same as most personal use trucks.

For '19-'20 6.7 Cummins with the hydraulic lifters require 10W30 or 5W40 oils and have moved away from 15W40 oils. Some who have ran 15W40 in these trucks have reported rattling or knocking noises.

[ShinerBock]

mr61impala wrote:
Let me preface this by saying this is NOT a recommendation.

I recently retired from UPS in the Automotive department, 9 years as a diesel mechanic and the rest of my career managing the shops.

UPS has the largest privately owned fleet of vehicles in the world so cost is a huge factor, I am going to tell you something you will not believe but trust me, it's true.

Around 20010, in an effort to reduce costs and after discussions with the various suppliers, UPS decided to use 10w30 exclusively in all delivery vehicles. Cummins was one of our suppliers who signed off on this decision.

We have been running 10w30 in all 5.9 and 6.7L Cummins, with a 15,000 oil drain interval since that time with no ill effects. Read that again. Most 6.7L engines exceed 500K miles with only water pump, turbo, injector, EGR valve and maybe EGR cooler replacement. I know of one in particular with over 600k miles that still only consumes 2 qts of 10w30 between those 15,000 mile oil changes.

The primary cause of CTD failure is injector failure, stripping the cylinder walls of lubricant. If it starts missing or smoking SHUT IT OFF until the cause is corrected.

Again this is not a recommendation, just interesting results of a huge real world reality.

This is kind of apples and oranges in terms of use. The reason why Cummins signed off on 10w30 for your trucks and many other applications likes it is due your constant stop/starts. Constant stop/starts is not good on many engine parts and adds a lot of wear to cylinder sleeves. Oil recommendations are generally based on applications and a UPS truck application is not the same as most personal use trucks.

[rhagfo]

blofgren wrote:

rhagfo wrote:

otrfun wrote:
If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

Well even if it is a bit more I like to be constant with the oil I put in my engines, and like it to be good quality.
This is part of the reason why, this is the tappet gallery on our 2001 Ram CTD at 300,000 miles.

Wow, that looks great! I only use top quality oil as well along with OEM filters in all of my vehicles.

I order my filters from Geno's Garage, yea they take a week to get here, but I order replacements when I use the ones I have, just in case I get some bad fuel.

[mr61impala]

Let me preface this by saying this is NOT a recommendation.

I recently retired from UPS in the Automotive department, 9 years as a diesel mechanic and the rest of my career managing the shops.

UPS has the largest privately owned fleet of vehicles in the world so cost is a huge factor, I am going to tell you something you will not believe but trust me, it's true.

Around 20010, in an effort to reduce costs and after discussions with the various suppliers, UPS decided to use 10w30 exclusively in all delivery vehicles. Cummins was one of our suppliers who signed off on this decision.

We have been running 10w30 in all 5.9 and 6.7L Cummins, with a 15,000 oil drain interval since that time with no ill effects. Read that again. Most 6.7L engines exceed 500K miles with only water pump, turbo, injector, EGR valve and maybe EGR cooler replacement. I know of one in particular with over 600k miles that still only consumes 2 qts of 10w30 between those 15,000 mile oil changes.

The primary cause of CTD failure is injector failure, stripping the cylinder walls of lubricant. If it starts missing or smoking SHUT IT OFF until the cause is corrected.

Again this is not a recommendation, just interesting results of a huge real world reality.

[blofgren]

rhagfo wrote:

otrfun wrote:
If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

Well even if it is a bit more I like to be constant with the oil I put in my engines, and like it to be good quality.
This is part of the reason why, this is the tappet gallery on our 2001 Ram CTD at 300,000 miles.

Wow, that looks great! I only use top quality oil as well along with OEM filters in all of my vehicles.

[otrfun]

rhagfo wrote:

otrfun wrote:
If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

Well even if it is a bit more I like to be constant with the oil I put in my engines, and like it to be good quality.

This is part of the reason why, this is the tappet gallery on our 2001 Ram CTD at 300,000 miles.

Granted, 5w-40, being synthetic, probably provides better protection under extreme conditions (i.e. operation at or below 0 deg). However, we've come to the conclusion it's not enough added protection under normal conditions (our M.O) to justify spending almost twice as much money for it every 6 mo.

Bottom line, we follow Ram's recommendation to use API CJ-4/CK-4, 15w-40 when temps are above 0 degrees (or 5w-40 synthetic when temps are 0 and below).

[rhagfo]

otrfun wrote:
If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

Well even if it is a bit more I like to be constant with the oil I put in my engines, and like it to be good quality.
This is part of the reason why, this is the tappet gallery on our 2001 Ram CTD at 300,000 miles.

[otrfun]

If Ram didn't require a 6-mo. OCI (truck's still under warranty), we'd probably use 5w-40 (3 gal. ~$60). However, we can't justify the extra expense for synthetic every 6-mo. Only put about 5k - 6k mi. on the truck between each 6 mo. oil change. We typically use whatever brand of API CK-4, 15w-40 that's on sale at Sam's Club or Costco (3 gal. ~$30).

[rhagfo]

I ran Delo 15-40 in the 2001, changed at 10K miles, had it tested and all was fine. Now with the 2016 switched to Valvoline 15-40 dino change at 6 months and about 6K miles due to warranty. Would love to go back to once a year 10K or so.

[Grit_dog]

It 100% doesn’t matter, although the 5-40 will be easier on extreme cold starts.
But I’ve lit off plenty of cold soaked Diesel engines, not plugged in, at -20 to -30 F with good old Dino 15-40. In those situations 5-40 is better though and plugged in even better.
If I was doing a winter oil change where it gets cold like where you live I’d go 5-40 just because.

[noteven]

15-40 sounds ok in your climate conditions.

It is trouble where it gets cold. Have a search for videos where engine oil is cold soaked then poured (or not). Imagine the top end of your engine waiting for oil after a cold start.