Engine oil

[austinsaltsman1]

What engine oil is everyone running in their 5th gen Cummins?

I know the recommended is 10w30 for warmer weather and 5w40 for cold.

I’ve been running 15w40 synthetic in every oil change other than what was shipped from factory. I’m at 94k miles, no issues and no sound from those hydraulic lifters. I didn’t realize the recommended changed for the 5th gen’s. Knowing what I know now I’m considering switching but still not sure if I will. I’m in FL we have summer basically year round and I tow regularly. If I do switch I’m leaning 5w40. Seems best of both worlds

 

[AH64ID]

There are no 5th gen Ram Cummins yet, these trucks are still 4th gen or 4.5 gen.

I run 5w-40, better cold and hot weather performance.

15w-40 full synthetics are likely fine, but not on the approved list.

How does one even come to run 15w-40 in a CGI 6.7?

 

[austinsaltsman1]

There are no 5th gen Ram Cummins yet, these trucks are still 4th gen or 4.5 gen.

I run 5w-40, better cold and hot weather performance.

15w-40 full synthetics are likely fine, but not on the approved list.

How does one even come to run 15w-40 in a CGI 6.7?

 

[austinsaltsman1]

I don’t understand while it isn’t on the “approved” list.

 

[AH64ID]

I don’t understand while it isn’t on the “approved” list.

Lifter issues.

I’m fairly certain synthetic 15w-40’s would be fine, but no need to risk it on my dime.

https://static.nhtsa.gov/odi/tsbs/2023/MC-10242795-9999.pdf

 

[austinsaltsman1]

Lifter issues.

I’m fairly certain synthetic 15w-40’s would be fine, but no need to risk it on my dime.

https://static.nhtsa.gov/odi/tsbs/2023/MC-10242795-9999.pdf

I know the reasoning It’s just hard to make sense of it.

Lifter issues.

I’m fairly certain synthetic 15w-40’s would be fine, but no need to risk it on my dime.

https://static.nhtsa.gov/odi/tsbs/2023/MC-10242795-9999.pdf

In hate the idea of going thinner, especially in my climate. But I guess the experts should know best… weird to see a day where they tell you not to put 15w40 in a Cummins

 

[austinsaltsman1]

I’m not good on the gens.. I have 21 3500 so I guess 4?

 

[AH64ID]

I know the reasoning It’s just hard to make sense of it.

It likely has to do with cold flow properties, which is why I don’t think a good synthetic 15w-40 would be an issue.

In hate the idea of going thinner, especially in my climate. But I guess the experts should know best… weird to see a day where they tell you not to put 15w40 in a Cummins

Even some of the bigger Cummins use 10w-30. 5w-40 is approved for all temps and has better cold and hot properties, thou it may slightly reduce fuel economy.

I’m not good on the gens.. I have 21 3500 so I guess 4?

4.5, which is 19-curr

 

[H3LZSN1P3R]

I know the reasoning It’s just hard to make sense of it.

In hate the idea of going thinner, especially in my climate. But I guess the experts should know best… weird to see a day where they tell you not to put 15w40 in a Cummins

Technically the hot viscosity is the same thats what the 40 means. Since you are not in cold climates i doubt the 15w40 syn would be an issue but still the 5w40 would be my choice 100%