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What oil for 2020 cummins? - Merged oil threads

When I had my first oil change done at the dealer I got it from (it was on them as part of the deal) they put in Rotella T5 10W-30. I have not noticed any issues with it aside from the fact that they overfilled it with it! I had to take it back and have them drain some out.
 
AH64ID said:
Everything I've seen says that the 19+ motors have a factory fill of 10w-30. It was the pre-18 motors that got 5w-40.
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I called customer service at Cummins just last week and ask them what oil they they recommended. they would not tell me! The book that came with my 2019 kinda danced around the question. Cummins customer service told me to call the Ram service dealership in my area and they would give me that information. I have 2019 3500 6.7 HO ENGINE and pull a heavy 4 horse trailer with living quarters we get below 0 and have few 100 + days. Service told me 5 W 40 syntheic for the Cummins 2019 and newer. I think there might have been some law suits on this engine! For what it’s worth!
 
glamb said:
I called customer service at Cummins just last week and ask them what oil they they recommended. they would not tell me! The book that came with my 2019 kinda danced around the question. Cummins customer service told me to call the Ram service dealership in my area and they would give me that information. I have 2019 3500 6.7 HO ENGINE and pull a heavy 4 horse trailer with living quarters we get below 0 and have few 100 + days. Service told me 5 W 40 syntheic for the Cummins 2019 and newer. I think there might have been some law suits on this engine! For what it’s worth!
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The owners manual doesn’t dance around it at all. For operation below 0°F you should run 5w-40.

Both 5w-40 and 10w-30 are good for extreme heat, thou the 5w-40 will probably do a little better IMO.

This is from the 2019 diesel supplement.

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^^^^^ What AH64ID said. The owner manual and chart are pretty clear, with no dancing.
I use 5w-40 full synthetic in my 2020 HO and I'll rarely see 30 degrees
 
When you read your manual there is no ambiguity to it ... Plain English . Maybe your concern was what brand ? Valvoline , Shell , Dello , Amzoil , Mobil , They are all good just be sure you use synthetic .
 
I am using 5W40 since day one. Never see freezing. However, I figure the 5 weight will flow better on start up and the 40 weight when hot provides a bit more protection when hot than 10W30. I am using Rotella T6.
 
CdnHO said:
I am using 5W40 since day one. Never see freezing. However, I figure the 5 weight will flow better on start up and the 40 weight when hot provides a bit more protection when hot than 10W30. I am using Rotella T6.
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What’s interesting is that most the 10w-30’s are thinner at 40°C than the 5w-40’s, but the 5w-40’s have better cold flow at extreme temps.
 
AH64ID said:
Yes, but that’s one of 2 temps viscosity is measured at with oil for ASTM D445. The other is 100°C, so 40°C is the “cool” one :D
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Interesting. Wonder what the differences are at normal ambient temperate such as 20C. However I do like the higher viscosity at operating temperatures when I am pulling my house down the road 6000 miles every year.
 
CdnHO said:
Interesting. Wonder what the differences are at normal ambient temperate such as 20C. However I do like the higher viscosity at operating temperatures when I am pulling my house down the road 6000 miles every year.
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I’m curious too.

I also like the 40wt for higher GCW’s.
 
CdnHO said:
Interesting. Wonder what the differences are at normal ambient temperate such as 20C. However I do like the higher viscosity at operating temperatures when I am pulling my house down the road 6000 miles every year.
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The 5W-40 should always flow better at low temps...for one thing, it's fully synthetic vs synthetic blend.
 
GirchyGirchy said:
The 5W-40 should always flow better at low temps...for one thing, it's fully synthetic vs synthetic blend.
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Yes it should. The 40°C viscosity index ratings are insteresting thou.

Not all 10w-30's are a synthetic blend, there are several that are full synthetics.
 
I’m still trying to learn about volatility. I’ve read (on FB nonetheless) rotella t6 has one of the highest, and is subject to burn off. Any oil nerds know what is one of the better ones to prevent burn off? I will probably snoop around BITOG site if I can’t get some good intel by my next OCI...
 
flan said:
I’m still trying to learn about volatility. I’ve read (on FB nonetheless) rotella t6 has one of the highest, and is subject to burn off. Any oil nerds know what is one of the better ones to prevent burn off? I will probably snoop around BITOG site if I can’t get some good intel by my next OCI...
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Generally speaking the closer the viscosity range the lower the volatility, so a 10w-30 should be less volatile than a 5w-40.

In the series of Amsoil I run the 10w30 is 4.5% and the 5w-40 is 9.2%. I did think about that when selecting 5w-40, but I don’t think it’s an issue. I have almost 11K miles on my oil and the level is at the same place it was when I changed, so unless it’s adding fuel at the same rate it burns off I don’t burn much, if any.

The test is done at 250°C and we don’t operate anywhere near that hot.
 
AH64ID said:
Generally speaking the closer the viscosity range the lower the volatility, so a 10w-30 should be less volatile than a 5w-40.

In the series of Amsoil I run the 10w30 is 4.5% and the 5w-40 is 9.2%. I did think about that when selecting 5w-40, but I don’t think it’s an issue. I have almost 11K miles on my oil and the level is at the same place it was when I changed, so unless it’s adding fuel at the same rate it burns off I don’t burn much, if any.

The test is done at 250°C and we don’t operate anywhere near that hot.
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Amsoil does not make sense for me as my oil ages out wayyy before it meets the mileage requirement. I do notice loss running the T6 usually when I tow hard through hill country. Then I saw the blurb on a 5G FB page about T6 being volatile compared to others (no mention as to what was best) so I guess I’ll do some research and testing.
 
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