Rotella T vs T6

[mudguy]

Just changed oil in my 6.7 cummins, decided to use Rotella T 15-40.

I've been using T6 for a while, simply decided to go cheaper this time.

How long do you think I could go on an oil change with the T? 10k? All highway miles.

 

[mudguy]

I should also mention, no emissions on this truck and lightly loaded.

 

[147_Grain]

The small cost difference might be used up in higher fuel consumption during the OCI.

The increased drag of a 15W-40 is more than a 5W-40.

 

[salv]

Rotella 15w40 will go as long as T6. Countless UOA'S show that dino HDEO's don't give anything up to the 5W40 synthetics.
Most fleets even stick to dino's.
If your temps stay above freezing, go with 15w40 dino.

 

[bvance554]

Originally Posted By: 147_Grain
The small cost difference might be used up in higher fuel consumption during the OCI.

The increased drag of a 15W-40 is more than a 5W-40.


Highly doubtful that he be able to notice and difference at all in fuel efficiency.

 

[Clevy]

Originally Posted By: bvance554
Originally Posted By: 147_Grain
The small cost difference might be used up in higher fuel consumption during the OCI.

The increased drag of a 15W-40 is more than a 5W-40.


Highly doubtful that he be able to notice and difference at all in fuel efficiency.


Agreed. During warm up fuel consumption may increase slightly but if the op is a start it and roll type driver the warm up will be as he drives so fuel consumption won't change much if at all

 

[Boczech]

Hey MudGuy I see you are up the road from me here in Sactown. Yes you are correct on doing 10k with the 15w40 since you pulled the emission equipment off. What kind of oil filter are you using ? LF16035 from Fleetguard is a good filter and Donaldson makes the ELF7349 which is rated slightly better in filtering. For the really cold starts you might want to consider the 10w30 or 5w40 if you don't have access to a power outlet.


Cheers
Bo

Originally Posted By: mudguy
Just changed oil in my 6.7 cummins, decided to use Rotella T 15-40.

I've been using T6 for a while, simply decided to go cheaper this time.

How long do you think I could go on an oil change with the T? 10k? All highway miles.

 

[dnewton3]

The only way to know for sure, how far either would go, is to run some trials with UOAs.

However, it is fair to generalize here and say that a Cummins, with no emissions equipment issues, in good mechanical conditions, can easily go 10k miles on any CJ-4 lube with no problems.

In theory, there might be a fuel differential, but the real world data won't bring it to light; it would only be during that very short time during warm up, and it would be slight to say the least.

If 10k miles is your hard OCI limit, the dino lube will do just fine, and save you money.

 

[jake88]

There may be a slight fuel economy improvement going from 15W-40 to 5W-40, but as noted above, most of the savings will be cold-start pumping losses. 10W-30 or even 5W-30 CJ-4 do show fairly significant fuel economy improvements (~4% for class 6).

Also always worth noting - over half of the wear on a typical engine occurs at start-up. Having a 5W-40 will be better than a 15W-40 for preventing cold-start wear.

 

[dnewton3]

Originally Posted By: jake88
... Also always worth noting - over half of the wear on a typical engine occurs at start-up. Having a 5W-40 will be better than a 15W-40 for preventing cold-start wear.


The vast majority of wear comes at the front end of an OCI; as the duration increases, wear practically drops to nil as the tribochemical barries establishes the anti-wear layer. See SAE 2007-01-4133 for proof. Once that barrier is in place, cold starts have very little effect on wear. I relaize that goes against what most folks think, but that does not make it any less true.

What you would get from the 5w rated lube is easier starting for quicker cranking in a diesel. In uber cold areas, that would make a difference as the speed of cranking helps create the heat of compression. But this "advantage" is overblown as most folks don't operate in an area that really brings out a distinguishable difference. And Truckee CA would be once of those places where it won't make a hoot of difference.

 

[GBL]

I agree with all except that members of the Donner Party might disagree with you regarding how cold it gets in Truckee. It's not Bismarck but it does gets chilly.

 

[dnewton3]

The average low in Truckee is 15 degF in Jan; it's not cold enough to required a 5w rated lube. The human condition of perception and the mechanical condition of reality are two totally different things here. Humans can perceive "cold" regardless of ambient temps; heck - my wife gets "cold" in summer when it's 70 deg F ... but that seems "hot" to me.

In an older IDI diesel, which relies on glow plugs and high cranking speeds to get started, a thinner lube could make a bit of a difference below zero F, especially if the batteries are a bit weak. But a modern DI diesel with an intake grid heater and common rail injection is not nearly as sensitive. Get below -20F, and then I'd agree with you. But that's not typical of Truckee at all.

Truckee just does not get cold enough to really bring out any major disparity of cold start performance between a 5w and 15w lube. And there won't be any wear difference. A syn will make the person feel better, but it's not at all likely to reveal any true performance differences.

And just for the sake of history, it was not really the cold that doomed the Donner party; it was the massive precipitation (snowstorm in October) that locked them into one location until they perished from limited resources. Had it been 30 deg F for one overnight, yet had they been able to move out easily the next few days, we'd never have heard of them and they would have passed into history unnoticed. Their fate was sealed because they were snowbound until spring. 36 of the 81 died. They had enough resources (admittedly limited) to endure the cold for a few nights, but they were unprepared (resources and skills) to live in that environment for months. The cold, combined with massive amounts of available moisture, caused an early snowstorm that essentially delayed them to death. It was not the "cold" that killed them overnight. And none of that means squat to the cold starts of the OPs modern 6.7L Cummins ...