2015 6.7 cummins, have I been doing it wrong? 5-40 M1 TDT

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I have a 2015 2500 6.7 Cummins that has had a Donaldson dbl7349 and eabp 100 bypass since new, with oci intervals at 7500mi using mobil 1 5-40 turbo diesel.
I live in Northern California, the truck sees no sub 40 degree weather. Truck is at 44,500 miles as of today.
However, the truck is used now for heavy towing. 17.5k 5th wheel toy hauler. I have stuck with 5-40, as it is synthetic and not conventional.

I am finding tonight I may be doing this wrong and need to be with a 15-40 instead?

Thanks for the help fellas. This place is always great to me, but I'm more of a lurker than a poster. You guys are far superior to me in your knowledge and intelligence, so I have more to gain by reading and respecting as opposed to posting.
 
Delo/Delvac/Rotella are the holy trinity of HDEO. And base stocks are improving where the NOACK and other specs are better. Further, 15w40 does not need lots of viscosity modifiers like the widespread variants do. (5w40).
Indeed, you can run what we run in larger engines. The motor will go a long ways and so will your cash.

OEM approval can get a bit more complex with 15w40 since drums make big money and gallons not as much.
So for example we are hearing Mobil Delvac Super comes FF in the new Duramax … but Mobil has not plastered that all over the place like they do the Dexos products.
Any of these above are solid in 15w40.
 
I don't know that it would be fair to say you're doing it "wrong", but probably you're wasting a LOT of money on syns a BP for 7.5k miles.
 
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Here it is from your owners manual. Yes, RAM asks you run 15W40 except when temperatures are below 0 degrees F. They don't want you starting your engine with 15W40 when temps are that low but are fine with you running 5W40. This all was asked by another person a few days ago. Maybe you read it?

The owners manual asks for CJ-4 and TDT is CJ-4.

I would say there is absolutely no issue. If you are nervous, perhaps have a UOA done and check if it sheared down at all in 7500 miles.

Like 4WD said, there are oils that the big rigs run, and your owners manual actually suggest them. Rotella is now out with a 15W40 oil that is perfect for your application. It meets Ck-4 and CJ-4 requirements. It also meets Cummins CES 20086 which supersedes CES 20081. I'm sure the Chevron fans are going to jump in now.
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2016 RAM Cummins Oil Requirement Part B.PNG
 
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My friend that uses the same truck for a hot shot operation runs 5w40 year round. The engine is fine. It's the transmissions that explode for no reason.

BTW do you have a CDL?
 
Originally Posted by J_mo
I have a 2015 2500 6.7 Cummins that has had a Donaldson dbl7349 and eabp 100 bypass since new, with oci intervals at 7500mi using mobil 1 5-40 turbo diesel.
I live in Northern California, the truck sees no sub 40 degree weather. Truck is at 44,500 miles as of today.
However, the truck is used now for heavy towing. 17.5k 5th wheel toy hauler. I have stuck with 5-40, as it is synthetic and not conventional.

I am finding tonight I may be doing this wrong and need to be with a 15-40 instead?

Thanks for the help fellas. This place is always great to me, but I'm more of a lurker than a poster. You guys are far superior to me in your knowledge and intelligence, so I have more to gain by reading and respecting as opposed to posting.


Do a UOA. You can increase your OCI I will bet. I surely have, but am not doing any towing.
 
M1 TDT is a very robust oil and with an HTHS of 3.8, it's capable of handling the heat. The 15W-40 has an HTHS of 3.7. The synthetic will likely be a better choice.
 
With that Engine, that OCI and your climate... Supertech 15w40 would most likely yield the same results..

TDT is good stuff.. if you are happy with it just keep it in longer.
 
My 2012 Ram has run on 5w40 for the last 100k plus miles. It doesn't care if it was Rotella T6, Mobil TDT, Delvac 1 or VPBE with Fleetguard, Donaldson and Baldwin filters over the last seven years with no issues or concerns.

UOA's would help considering you have a bypass.
 
these engines are not hard on oil, ith over 1.5 million miles combined on my cummins trucks, run what ever is on sale. i change mine at 10K.
i like the Travellers from tractor supply, and i get valvoline in bulk. i've ran the mobile MXf2, again, what ever is on sale. the engine doesnt care one iota, long as it's change when it should be, and thats about the 500 hour mark.

So to recap, run the correct type of oil for a diesel, of the correct grade for your climate, can be 5/40 or 15/40, makes no difference to the engine, only your bank account. change it when it should be.
 
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Thanks for all the replies guys!
Now that rotella has come out with a 15-40 variant T6 in synthetic that's what I'll swap over to.
Majority of those miles are highway. I dont drive the truck much but to pull our 5ver these days, so its annually instead of miles. It sees a few trips a year and spends the rest of it's time in hibernation in the garage.
I daily drive my 6leaker, which I think next go I'll give a run of that 15-40 T6 also. I just did the oil 2 weeks ago with some m1 tdt I had.
 
Originally Posted by J_mo
I have a 2015 2500 6.7 Cummins that has had a Donaldson dbl7349 and eabp 100 bypass since new, with oci intervals at 7500mi using mobil 1 5-40 turbo diesel.
I live in Northern California, the truck sees no sub 40 degree weather. Truck is at 44,500 miles as of today.
However, the truck is used now for heavy towing. 17.5k 5th wheel toy hauler. I have stuck with 5-40, as it is synthetic and not conventional.

I am finding tonight I may be doing this wrong and need to be with a 15-40 instead?

Thanks for the help fellas. This place is always great to me, but I'm more of a lurker than a poster. You guys are far superior to me in your knowledge and intelligence, so I have more to gain by reading and respecting as opposed to posting.
.

The Cummins engine just doesn't care about what oil is in it. 5w40 or 15w40. It doesn't shear 5w40 towing in hot weather. I have hot-shotted year-round with RT6 5w40 on oil change intervals as long as 37,000 miles. I have hot-shotted using conventional 15w40 on OCI's as long as 29,000 miles. Oil analyses have never shown any viscosity loss, excessive wear metals, or acid neutralization ability. If you are not going to extend OCI's past 12k miles, synthetic 15w40 is a waste of money. If you want to adhere to the 7500 mile OCI, conventional 15w40 from Mobil, Shell, Chevron, or Kendall will do the job for hundreds of thousands of miles.
 
I don't put a lot of miles on my truck, about 12k in almost three years. I've used Shell Rotella 15w40, changed solely on time. I've started it in ambient temps close to 0° F. It pretty much only tows a 26k+ 5th wheel toy hauler. No issues.
 
Originally Posted by 02SE
I don't put a lot of miles on my truck, about 12k in almost three years. I've used Shell Rotella 15w40, changed solely on time. I've started it in ambient temps close to 0° F. It pretty much only tows a 26k+ 5th wheel toy hauler. No issues.



This is basically me. I have put 3500 miles since last june (2018). I change it annually or 7500mi. Annually nearly always comes first With the exception of putting 20k commute miles on in a year in 2017. the truck has seen very little annual miles. I purchased new dec 1 2014.
2017 I bought our grand design and it has had a handful of tow miles added. Somewhere in the 7-8k range I'd assume without checking the truck.

The truck also has no regenerative soot devices pe se.
 
Originally Posted by J_mo
Thanks for all the replies guys!
Now that rotella has come out with a 15-40 variant T6 in synthetic that's what I'll swap over to.
Majority of those miles are highway. I dont drive the truck much but to pull our 5ver these days, so its annually instead of miles. It sees a few trips a year and spends the rest of it's time in hibernation in the garage.
I daily drive my 6leaker, which I think next go I'll give a run of that 15-40 T6 also. I just did the oil 2 weeks ago with some m1 tdt I had.



On paper the T6 and T4 are very close as far as VOAs from what ive seen. I didnt see anything fantastic about the T6.. maybe just a 'feel good' because it says synthetic.
 
Only shaffers and amsoil are any good all the rest is garbage... Lol
But the reports were great especially with towing 10 to 20k lb 100% of the time.
 
Originally Posted by Killer223
these engines are not hard on oil, ith over 1.5 million miles combined on my cummins trucks, run what ever is on sale. i change mine at 10K.
i like the Travellers from tractor supply, and i get valvoline in bulk. i've ran the mobile MXf2, again, what ever is on sale. the engine doesnt care one iota, long as it's change when it should be, and thats about the 500 hour mark.

So to recap, run the correct type of oil for a diesel, of the correct grade for your climate, can be 5/40 or 15/40, makes no difference to the engine, only your bank account. change it when it should be.

+1
 
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