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 > 5W40 or 15W40 in 6.7 CTD?

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time2roll

Southern California

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Posted: 11/04/20 12:09pm Link  |  Quote  |  Print  |  Notify Moderator

How about compromise with 10W40? Go ahead and mix the two if needed.


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FishOnOne

The Great State of Texas

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Posted: 11/04/20 04:04pm Link  |  Quote  |  Print  |  Notify Moderator

ShinerBock wrote:

There is not much difference in a used oil analysis between 15k oil at a year and 15k oil at 6 months. The detergents and other compounds in the oil is slightly less, but still well within spec. In fact, it would be next to impossible to tell the difference between the two.

Some like to error on the side of caution because they do not know any better, and I get that. If you have never performed a UOA to know exactly how oil holds up, then by all means change it every 6 months if it makes you feel better and is "cheap insurance" to you. I, on the other hand, would rather know and have hard data when making such decisions. I change it once a year because I know there is no significant difference between the two time frames based on UOA's from my own truck and the thousands of 6.7L Cummins engines we perform UOA's on at work.


The 6 month oil change is probably to cover for B20 diesel, short commute and town driving.


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otrfun

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Posted: 11/04/20 07:16pm Link  |  Quote  |  Print  |  Notify Moderator

LIKE2BUILD wrote:

otrfun wrote:

LIKE2BUILD wrote:

. . . Another point for me is oil change frequency. The manual says to change oil every 15,000 miles or 500 hours and I don't even come close to that mileage in a year. So, I just change my oil once a year and with the 5W40 I'm covered for any temperature range and I don't have to worry about it.

KJ
Our 2016 Ram Cummins OCI is 15,000 mi., 500 hours, or 6 months, whichever comes first. Your profile says you have a 2014 Ram Cummins. Is the OCI different for the 2014's?
You're right, it does say 6 months. However, I'm comfortable with the additive packages in the synthetic oil and use the 1 year time frame. When I changed oil this summer I had only put 5,200 miles on the truck since July of 2019. If I would have changed oil at 6 months it would have been less than 25% used (on a mileage basis).

KJ
I was just curious, thanks. We have an 8y/120k OEM extended warranty, so we'll be sticking with the 6 mo. OCI for a few more years/miles. If we still have the truck after 8/120 we'll probably go to a 12 mo. OCI using 5w-40.

With that being said, gotta wonder which would keep my Cummins runnin' the longest? 15w-40 changed every 6 mo. or 5w-40 changed every 12 mo.? lol! [emoticon]

Grit dog

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Posted: 11/04/20 07:44pm Link  |  Quote  |  Print  |  Notify Moderator

^Honestly, the chance of oil related failure being the first thing that gives up the ghost or causes you to buy a new vehicle is highly unlikely even with “normal” OCIs.


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blofgren

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Posted: 11/04/20 08:12pm Link  |  Quote  |  Print  |  Notify Moderator

otrfun wrote:

LIKE2BUILD wrote:

otrfun wrote:

LIKE2BUILD wrote:

. . . Another point for me is oil change frequency. The manual says to change oil every 15,000 miles or 500 hours and I don't even come close to that mileage in a year. So, I just change my oil once a year and with the 5W40 I'm covered for any temperature range and I don't have to worry about it.

KJ
Our 2016 Ram Cummins OCI is 15,000 mi., 500 hours, or 6 months, whichever comes first. Your profile says you have a 2014 Ram Cummins. Is the OCI different for the 2014's?
You're right, it does say 6 months. However, I'm comfortable with the additive packages in the synthetic oil and use the 1 year time frame. When I changed oil this summer I had only put 5,200 miles on the truck since July of 2019. If I would have changed oil at 6 months it would have been less than 25% used (on a mileage basis).

KJ
I was just curious, thanks. We have an 8y/120k OEM extended warranty, so we'll be sticking with the 6 mo. OCI for a few more years/miles. If we still have the truck after 8/120 we'll probably go to a 12 mo. OCI using 5w-40.

With that being said, gotta wonder which would keep my Cummins runnin' the longest? 15w-40 changed every 6 mo. or 5w-40 changed every 12 mo.? lol! [emoticon]


It would probably make no difference as long as you aren't exceeding the mileage specifications. I'm not the least bit worried about the 1 year OCI that I have been using for several years now.


2013 Ram 3500 Megacab DRW Laramie 4x4, 6.7L Cummins, G56, 3.73, Maximum Steel, black lthr, RAM 20k sliding hitch, Retrax, Linex, and a bunch of options incl. cargo camera
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rhagfo

Portland, OR

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Posted: 11/04/20 08:26pm Link  |  Quote  |  Print  |  Notify Moderator

blofgren wrote:

otrfun wrote:

LIKE2BUILD wrote:

otrfun wrote:

LIKE2BUILD wrote:

. . . Another point for me is oil change frequency. The manual says to change oil every 15,000 miles or 500 hours and I don't even come close to that mileage in a year. So, I just change my oil once a year and with the 5W40 I'm covered for any temperature range and I don't have to worry about it.

KJ
Our 2016 Ram Cummins OCI is 15,000 mi., 500 hours, or 6 months, whichever comes first. Your profile says you have a 2014 Ram Cummins. Is the OCI different for the 2014's?
You're right, it does say 6 months. However, I'm comfortable with the additive packages in the synthetic oil and use the 1 year time frame. When I changed oil this summer I had only put 5,200 miles on the truck since July of 2019. If I would have changed oil at 6 months it would have been less than 25% used (on a mileage basis).

KJ
I was just curious, thanks. We have an 8y/120k OEM extended warranty, so we'll be sticking with the 6 mo. OCI for a few more years/miles. If we still have the truck after 8/120 we'll probably go to a 12 mo. OCI using 5w-40.

With that being said, gotta wonder which would keep my Cummins runnin' the longest? 15w-40 changed every 6 mo. or 5w-40 changed every 12 mo.? lol! [emoticon]


It would probably make no difference as long as you aren't exceeding the mileage specifications. I'm not the least bit worried about the 1 year OCI that I have been using for several years now.


Well, diesels don't destroy oil the same as gas, think gas is a solvent, diesel is an oil.
Our 2001 Ram 2500 CTD ran 15-40 Delo 12 months, 10K miles, had TBN tested to get there comfortably. The last test Blackstone stated plenty of additives left, go for 12,500, I stuck to 10K.
Earlier I added pictures of the tappet gallery when I needed to change the cover gasket at 300K, very clean!
I am seriously considering going by the change indicator, and spend the extra $10 for the TBN, and keep the results if there is an issue.

This six months I put 7,676 miles on the oil, and the change indicator was half way to change.


Russ & Paula the Beagle Belle.
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Cummins12V98

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Posted: 11/04/20 10:05pm Link  |  Quote  |  Print  |  Notify Moderator

I have a Blackstone report for all oil changes. All but last one have been 15k. They say I can go longer after warranty is up.

I run AMZ/OIL Signature Series 15/40. Cold pour point is not much different than their 5-40.


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noteven

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Posted: 11/05/20 06:28am Link  |  Quote  |  Print  |  Notify Moderator

Cold 5W40 vs 15W40

Cold oil comparison

ShinerBock

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Posted: 11/05/20 06:37am Link  |  Quote  |  Print  |  Notify Moderator

blofgren wrote:


It would probably make no difference as long as you aren't exceeding the mileage specifications. I'm not the least bit worried about the 1 year OCI that I have been using for several years now.


You are correct. The time frame of 6 months doesn't matter as long as it is changed with a certain mileage or engine hours. As I stated earlier, no oil analysis would be able to tell the difference between 15k mile oil at 6 months or 15k mile oil at 12 months. The 15k interval with the Cummins is even with non-synthetic 15w40.

otrfun

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Posted: 11/05/20 08:01am Link  |  Quote  |  Print  |  Notify Moderator

ShinerBock wrote:

blofgren wrote:


It would probably make no difference as long as you aren't exceeding the mileage specifications. I'm not the least bit worried about the 1 year OCI that I have been using for several years now.
You are correct. The time frame of 6 months doesn't matter as long as it is changed with a certain mileage or engine hours. As I stated earlier, no oil analysis would be able to tell the difference between 15k mile oil at 6 months or 15k mile oil at 12 months. The 15k interval with the Cummins is even with non-synthetic 15w40.
Makes perfect sense to me.

Then why the heck does Ram have a 6 mo. OCI on their late model Cummins?

They have "severe" duty maintenance intervals for other things like the tranny and differential. Why wouldn't they recommend 6 mo. OCI's for severe duty and 12 mo. for non-severe?

Ram obviously feels there's something that's degrading the oil over time---something that's not mileage related. Some kind of water, corrosion, or fuel contamination issue?

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