New Cummins H.O. TD

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Apr 14, 2007
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SD
Hello,

Simple question: is there any reason for me not to use Shell Rotella T6 15-40 in my 2020 Ram 3500 with a Cummins High Output turbo diesel? This truck is our daily driver plus it has to pull our 20k fifth wheel around America. The manual recommends 10w30 oil, with a 15k OCI.

Looking for an oil choice that is easy to find anywhere, and T6 is popular and readily available. I intend to go no more than 10k OCI.

Thanks for the input!
 
What oil does Cummins / owner manual recommend ? Over the road semis run semi trucks run million+ miles on miles the HDEOS from Chevron, Shell, Mobil and other reputable blenders.
 
If my memory serves me correctly the manual does not suggest the use of 15w-40, but it does list 5w-40 as an alternative. Check it out.
 
I'm a semi mechanic for ups. Our yard shifter trucks that move semi trailers at the sort hubs have a 6.7 Cummins, but have a lower output. Even the 2020 Kalimar still specifies 15W40 and 250 hour OCI's. those engines hit 25k using Delo 15W40 and a.Baldwin filter before they get worn out. Use the 10w30 without concern. Drive the truck smooth and sane and the engine should outlive the truck.
 
Go for the 5W40 Rotella T6 like the manual recommends as the alternative while under warranty.

I run the 5w40 T6 in my 6.7 year around for 10K change intervals with a Donaldson DBL7349.
 
T5 10W30 is a pretty good oil, too-think with that kind of investment & towing, I would be tempted to try them both and see which one delivered better results.
 
JMO towing 20,000 lbs I would try 15w40 in this mix with those and do a UOA. You may find that the 15w40 is more shear stable than the 5w40, and may give you the lowest iron wear. The 10w30 is the most shear stable, but these engines don't shear the oil like a HEUI PSD.
 
Other that the lower starting ability of a 5W oil the 15W-40 is the better oil.
 
Go for the T6 5w40. Should be just as easy to find as 15w40. I wouldn't worry about shearing if your going to do 10k OCI.
 
I think the Rotella 5W-40 is way more impressive as an oil than the T6 15W-40 spec wise.

I would use almost any other 15W-40 than the T6 - if I went the 15W-40 route....

T6 - 5W-40 is OK with warranty spec and a great oil, so I would stay with that until warranty was up.
 
t6 5w-40, Delo LE syn 5w-40 or M1 TDT 5w-40 all easy to find probably would use one of them
 
Last edited:
Originally Posted by HighwayRanger
Hello,

Simple question: is there any reason for me not to use Shell Rotella T6 15-40 in my 2020 Ram 3500 with a Cummins High Output turbo diesel? This truck is our daily driver plus it has to pull our 20k fifth wheel around America. The manual recommends 10w30 oil, with a 15k OCI.

Looking for an oil choice that is easy to find anywhere, and T6 is popular and readily available. I intend to go no more than 10k OCI.

Thanks for the input!


Simple answer; no reason not to.

Here's a VOA for it.

https://www.bobistheoilguy.com/foru.../ck4-shell-rotella-t6-15w-40#Post5315970

I like to see Moly so I'm not using it but as has been suggested, tons of professional truckers out there using it without issue.
 
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