Tip Cummings Warning!

[Bwk]

Folks, I have a 2021 superC with a cummins 6.7 diesel.
I buy an f250 every three years and put 130,000 into the last one, 155,000 on them
Many moons ago, working for an oil company, im an oil fanatic and changed my own even on the company vehicles.
So all I have is Moble1 for the cars and 15w40 T6 for the diesels.
So at 3000 miles on the Cummins, I dumped the stock crude that came in the Cummins and put 15w40 T6 in it.at 13,000 did it again two weeks ago.
Now I found out the 6.7 valve train was redesigned in 2020, and you must use 5w40, or the 15w40 will cause sludge build-up in the valve train.
Duh on my part, but going on an 1800-mile round trip next week and then will change to the correct grade.
Be aware!!!

 

[tdkkart]

Here for the replies to this one...............

 

[Rich W.]

There is this but it only refers to Mopar:

https://static.nhtsa.gov/odi/tsbs/2020/MC-10178698-9999.pdf

I’d want to see something from Cummins regarding class 7 and 8 trucks before running 5w-40 or 10W-30. By 2020 they had pushed HP/tq in pick-ups to 400/1000 (now they say 420/1075) and to accomplish that they may have had to use different valve train specs.

So it may or may not apply to 300/660 - 360/800 engines. If nothing else, one could always check their owners manual/documentation that came with the vehicle.

@Bwk what does your Cummins manual say?

From the bulletin:
NOTE: This bulletin applies to vehicles equipped with a 6.7L I6 Cummins Turbo Diesel Engine (Sales Code ETK, ETL, ETN or ETM)

 

[Bwk]

The Manual says 5w40 Moble stock crude.
That was all I needed to see to know they were bought and paid for to say that.
I will only use synthetic period.
I did call rush and a Cummins service manager. (mine is in the 300 hp bracket)
I had to give both the engine serial to look up
And I made it clear if this was for better gas mileage, im not interested.
So I now have a 5-gallon pail of 5w40.
I do not like it!

 

[MemoriesByTheMile]

That would have caught me by surprise. On our older SuperC we are using 15w40 in the Cummins and in the Onan 12k gen.

Seems that 5w40 would only be for cold temps.

This goes to show that I should read all manuals for all new purchases, maybe even purchases in the past few years.

Thanks for sharing.

 

[Bwk]

It makes no sense to me.
I'm wondering since the love stock crude oil now, if that's the problem but not in synthetic.
I will keep asking.

Guess im getting old as had a hard time putting in wifes car 5w40 European grade in a twin turbo v8.
And 5w30 in a Ferrari.
One of the Toyota's now call for 0w16
But very tight bearing gaps so understand that.

 

[Bayouownbeer]

Folks, I have a 2021 superC with a cummins 6.7 diesel.
I buy an f250 every three years and put 130,000 into the last one, 155,000 on them
Many moons ago, working for an oil company, im an oil fanatic and changed my own even on the company vehicles.
So all I have is Moble1 for the cars and 15w40 T6 for the diesels.
So at 3000 miles on the Cummins, I dumped the stock crude that came in the Cummins and put 15w40 T6 in it.at 13,000 did it again two weeks ago.
Now I found out the 6.7 valve train was redesigned in 2020, and you must use 5w40, or the 15w40 will cause sludge build-up in the valve train.
Duh on my part, but going on an 1800-mile round trip next week and then will change to the correct grade.
Be aware!!!

I have 2023 model the chassis is 2022 it has a isb 6.7 just like yours and this is a page out the Cummins manual

 

[Bayouownbeer]

I have 2023 model the chassis is 2022 it has a ISB 6.7 just like yours and this is a page out the Cummins manual

Stick with the 15w-40 buddy

 

[TheLooks]

The only reason for thin oil at start up is extreme cold weather. I use 15-40 in the summer here in Tenn. in a Ram that specs 0-40. I have read oil threads by the hundreds for years. In all seriousness, a good 10-30 will work in anything in the lower 48 just fine. All year long.

 

[Bayouownbeer]

Folks, I have a 2021 superC with a cummins 6.7 diesel.
I buy an f250 every three years and put 130,000 into the last one, 155,000 on them
Many moons ago, working for an oil company, im an oil fanatic and changed my own even on the company vehicles.
So all I have is Moble1 for the cars and 15w40 T6 for the diesels.
So at 3000 miles on the Cummins, I dumped the stock crude that came in the Cummins and put 15w40 T6 in it.at 13,000 did it again two weeks ago.
Now I found out the 6.7 valve train was redesigned in 2020, and you must use 5w40, or the 15w40 will cause sludge build-up in the valve train.
Duh on my part, but going on an 1800-mile round trip next week and then will change to the correct grade.
Be aware!!!

That’s for the 6.7 they use in the dodge HD trucks not the B6.7 used in the freightliner chassis. See this link for the B6.7

https://mart.cummins.com/imagelibrary/data/assetfiles/0070492.pdf