Synthetic or Comventional?

[CalebMD1024]

Hi all, new to the Cummins world. Just picked up a 16 2500 a couple weeks back with 65k on the ticker. I’ve owned powerstokes and an Ecodiesel.

In my 6.7 power stroke, I could use synthetic or conventional, but noticed a big difference with the engine running smoother with conventional. Idled smoother, was a bit quieter, etc. Switched from T6 to T4 for that reason.

Does such a difference exist for the Cummins?

BTW, I spelled conventional wrong in the forum topic. Any ideas how to fix?

 

[AH64ID]

I’ve never noticed a difference on my Cummins, but really haven’t ran much conventional oil. On other vehicles synthetic has quieted them up a little, but nothing to write home about. I use a 15w-40 synthetic in my Cummins.

I can’t think of any good reason why you would have seen that difference on a power stroke. Maybe it didn’t like the thinner properties at startup, but even that seems odd?

 

[lpennock]

I’ve never noticed a difference on my Cummins, but really haven’t ran much conventional oil. On other vehicles synthetic has quieted them up a little, but nothing to write home about. I use a 15w-40 synthetic in my Cummins.

I can’t think of any good reason why you would have seen that difference on a power stroke. Maybe it didn’t like the thinner properties at startup, but even that seems odd?

Power Strokes use oil pressure in the injectors to actuate them. One of the first trouble shoot techniques on a poor running PS is to change the oil.

 

[AH64ID]

Power Strokes use oil pressure in the injectors to actuate them. One of the first trouble shoot techniques on a poor running PS is to change the oil.

Pretty sure HPOP’s went away for the 6.7... ya know the CP4 fiasco.

Oil quality is still very important for HPOP truck thou.

 

[Cummins12V98]

I run AMZ/OIL Signature Series 15-40 with great test results even at 15k changes. Be sure to run the FleetGuard StrataPore filter or Donaldson Blue or the relabeled AMZ/OIL Filter.

 

[Wiredawg]

I choose to run synthetic in everything I own since around 2003, but everything before that ran fine on dino oil. I think more important is changing oil at minimum prescribed intervals or less, use name brand oil, and one of the premium oil filters previously mentioned.

I imagine oil discussions are the most abundant and the most debated here on the TDR. The real deal is no one is wrong and everyone is right, minus the attitudes and ferver.

Cheers, Ron

 

[Cummins2014]

IMHO T4 is as good as any, used it in two different diesels now for nearly 22 years. Plus the filters mentioned above . I stretch mine out now more on time then miles, just don't put enough on to follow the manual now thats its off warranty.

 

[JR]

It depends on where you live, Cummins recommends synthetic if you consistently live in sub 0*F weather, other than that conventional oil will be just fine.

And welcome to TDR!

 

[gsbrockman]

It depends on where you live, Cummins recommends synthetic if you consistently live in sub 0*F weather, other than that conventional oil will be just fine.

And welcome to TDR!

To extrapolate on the above......5W40 synthetic when anticipated temperature ranges are at or below 0*F, since nowadays there are several 15W40 oils offered in synthetic.

 

[AH64ID]

To extrapolate on the above......5W40 synthetic when anticipated temperature ranges are at or below 0*F, since nowadays there are several 15W40 oils offered in synthetic.

The manual has never talked about 15w-40 synthetics as even today they aren’t common.

I run, and have for more than 10 years, a 15w-40 synthetic in any temp I encounter.L, which has been cold starts below -20°F.

The pour point on 15w-40 synthetic and 5w-40 synthetic, of the brand/style oil I run, is only 5°F higher at -40°. There are other benefits to the 15w-40 over 5w-40, which is why I run it.

Neither is a bad in nearly all temperature ranges, but if I lived in arctic style climates I’d probably run a 0w-40 synthetic.

 

[gsbrockman]

Just going by the visual aid that’s in the diesel supplement, @AH64ID

 

[JR]

To extrapolate on the above......5W40 synthetic when anticipated temperature ranges are at or below 0*F, since nowadays there are several 15W40 oils offered in synthetic.

You are correct, the book does state that. But ask most any commercial owner/operator or farmer what they run, in a CTD or otherwise, and one gets the picture it's really not an issue unless you see constant below zero temps. The occasional dip below that threshold or anticipating it to do so is not worth getting worked up over.

 

[AH64ID]

Just going by the visual aid that’s in the diesel supplement, @AH64ID

Yeah, just wanted to point out synthetic 15w-40 has been out awhile and never been discussed. I also doubt it ever will.

 

[DHayden]

This blog will give you more reading than you can handle. An Engineer with no dog in the fight tests hundreds of oils and shows his results. A lot of long winded stuff in the beginning and test results farther down. You can use F3 to use find option and enter oil you are interested and where it ranks. Covers synthetic and dino oils.

https://540ratblog.wordpress.com/

 

[Dick Langendorff]

This is what I have used since 1989 when I bought my first Cummins.
That is what Cummins recommends and that is what I did.
The 1989 had 123,000 on it when I got my 2004. The 04 currently has 282,000 on it.
Never have to add oil. I still get the same mpg around town or towing my 33ft 5th wheel.
I do my own service and get Blackstone reports on occasion.
The only major repair has been the transmission OD.
Other that that, listen to it and drive it.

 

[Killer223]

when subjected to combustion chamber gasses, synthetics don't offer much over the dino oil. they do have better cold flow properties, but in these engines that are not hard on oil, eh, all that being the same, i have over 900,000 miles on a few cummins engines. and the one thing i learned was use the oil thats on sale, of the correct grade for the climate i was running in. changes when it should be. usually around the 500 hour mark.

 

[CalebMD1024]

Thanks for the good info, all. Having bought it used, I have no way of telling how the previous owner treated it. Hopefully well!

I’ve got a few recommended services coming up according to the manual, so I’m going to explore TDR further and learn more about them.

thanks, all!

 

[DeansRedRam]

I'll always run a synthetic, to my understanding it is made by replicating only the GOOD properties of a conventional. Plus its only slightly more expensive for the peace of mind IMHO, in that respect its worth every penny.

In the winter-Spring I'll run 5w-40. We won't see much of 0 degree weather but I'll say this oils in the truck till its 50 degrees outside. I notice lower oil pressure at startups (5w oil flows better at cold temps) and I get oil pressure faster which makes me happy.

I mean the 40 part of the oil is really the only concern, in theory its the same viscosity as a 15w-40 at operating temp, right?

 

[Cummins12V98]

Waste of time!!! Run 15-40 "FULL" Synthetic year round UNLESS you are in EXTREME conditions. Simply compare the pour points on both grades.

 

[DeansRedRam]

Waste of time!!! Run 15-40 "FULL" Synthetic year round UNLESS you are in EXTREME conditions. Simply compare the pour points on both grades.

Which is a waste of time?