Diesel Oil Questions

[Doug Hillary]

Hi,
Gokhan - The fuel saving benefits between these two viscosities occur primarily in the 30mins or so after a cold start - in favour of the 5W-40. After that it is a matter of the engine's application including a wide range of influences

Many engine Manufacturers simply have a minimum HTHS viscosity as a part of their lubricant specification/recommendation!

In the case of my own engines the average operating oil temperature was 103C (217F) and the maximum attained was 112C (234F)

Localised oil temperatures (around turbos etc.) reach much higher temperatures of course

 

[Gokhan]

Originally Posted By: roadrunner1
I have yet to see any evidence of increased wear between 10w-30/15w-40.
In my own experience with UOA's I have seen LESS wear using 10w-30.

The engine manufacturer offers both grades as acceptable, so its not like we are venturing off into unknown territory with a lighter grade. The myth of needing a 40wt. in medium/heavy diesel applications is eroding fast.

For many years these engines ran for thousands of hours on straight 30wt.

Note that we're talking about heavy-duty diesel engines, not small diesel engines. I don't think you've been doing UOAs on heavy-duty diesel engines.

The following single sentence that is repeated many, many times on Pages 14 - 16 of the Caterpillar fluid reference manual[/url that was posted above summarizes what oil viscosity you should use in a heavy-duty diesel engine:

"Generally, use the highest oil viscosity that is allowed for the ambient temperature when you start the engine."

If you read those pages of the Caterpillar fluid reference manual, you'll see that they tabulate the temperatures for 0W-30, 10W-30, 5W-40, and 15W-40 grades. Then, they make the statement in that single sentence. Therefore, Caterpillar is clearly recommending 15W-40 for this engine for Seattle temperatures over 5W-40, 10W-30, or 0W-30. For me a manufacturer's oil recommendation can't be any more clear than this.

 

[Ramblejam]

Originally Posted By: Gokhan

Thank you Doug.

The minimum HTHS viscosity SAE spec for 5W-40 is 3.5 cP. The minimum SAE spec for 15W-40 is 3.7 cP. Typically 15W-40 will have an HTHS viscosity of about 4.3 cP and 5W-40 will be have an HTHS viscosity of about 3.7 cP. This is a substantial difference. If they both had the same HTHS viscosity, there would be no fuel-economy benefit of using 5W-40 because the fuel economy is determined by the HTHS viscosity (= hydrodynamic friction).


Mr. Hillary, based on real-world usage, completely decimates your position...and the response is "thank you"? Wow.

Secondly, Amsoil CJ-4 5W-40 comes in at 4.1cP, and they've got plenty on their website showing improved fuel economy when compared to a similar HT/HS 15w-40.

Originally Posted By: Gokhan
The first reference is a marketing brochure and they cleverly omit any wear comparison against 15W-40.

The second reference clearly states that 10W-30 is for the newer, 2013+ engines. These newer engines are designed more tolerant to smaller oil-film thickness of 10W-30. It's the same as newer gasoline engines being built tolerant to smaller oil-film thickness, such as 0W-16 viscosity coming soon for 2015+ gasoline engines.

An impartial wear comparison is in the Chevron/Oronite presentation I linked above, showing that there is even significant wear increase when going down in viscosity from 15W-30 to 10W-30.


So your entire stance relies on one page of a PDF presentation, where an artificial bench test was ran on artificial (15w-30) oils? Come on now, Gokhan. You're better than that.

No, the media release from Kenworth doesn't state anything about solely being utilized in 2013+ engines. Instead, there's a need in the marketplace for an oil with enhanced fuel economy, and Chevron has a product to meet that request. Hence, factory fill in 2013.

5w-40, or 10w-30 can be safely utilized with exceptional wear rates in any heavy-duty diesel application where the OEM has approved such a viscosity.

 

[Gokhan]

Originally Posted By: Doug Hillary
Hi,
Gokhan - The fuel saving benefits between these two viscosities occur primarily in the 30mins or so after a cold start - in favour of the 5W-40. After that it is a matter of the engine's application including a wide range of influences

Many engine Manufacturers simply have a minimum HTHS viscosity as a part of their lubricant specification/recommendation!

In the case of my own engines the average operating oil temperature was 103C (217F) and the maximum attained was 112C (234F)

Localised oil temperatures (around turbos etc.) reach much higher temperatures of course

Hello Doug,

Your statement about fuel economy is not correct. The biggest source of frictional loss in an engine is hydrodynamic friction (internal fluid friction of the oil, not the friction of moving surfaces) and that is determined by the HTHS viscosity. See the HDEO fuel-economy charts in the Chevron/Oronite presentation.

Yes, of course, there is a minimum spec on the HTHS viscosity by the manufacturer, as it determines the minimum oil-film thickness, which is critical to guard against engine failure due to excessive wear.

There is also a misconception about the "high-temperature" in the high-temperature, high-shear (HTHS) viscosity. High-temperature doesn't refer to the average temperature of the oil circulating in the engine. It doesn't refer to the average bearing or ring temperature either. It refers to an instantaneous temperature peak where the oil is squeezed within the bearing, which is caused by a pressure peak at the same point. This temperature is much higher than the average oil temperature or bearing temperature. See the pressure distribution within the bearing:

 

[Ramblejam]

Originally Posted By: Gokhan
Originally Posted By: Doug Hillary
Hi,
Gokhan - The fuel saving benefits between these two viscosities occur primarily in the 30mins or so after a cold start
Your statement about fuel economy is not correct.


When comparing a 5w-40 vs. 15w-40, Mr. Hillary is absolutely correct.

 

[Gokhan]

Originally Posted By: Ramblejam
So your entire stance relies on one page of a PDF presentation, where an artificial bench test was ran on artificial (15w-30) oils?

This is not true. The relationship between HTHS viscosity and wear for heavy-duty diesel engines is well known and repeated in many publications.

The most relative publication in this case is the Caterpillar's oil recommendation. They say: "Generally, use the highest oil viscosity that is allowed for the ambient temperature when you start the engine." So, this is the end of story as far as the oil recommendation for this engine is concerned. Caterpillar's statement is implying that, as long as you can start the engine, a thicker oil will result in less wear.

There are plenty of references on this. See for example the nice graph of wear vs. HTHS viscosity on the Page 4 of this Chevron Oronite reference (PDF link).

Or see this Lubrizol article on the challenges of upcoming PC-11 low-HTHS-viscosity (less than 3.5 cP) HDEO oils.

On top of all this, use of 15W-40 is clearly economically most sound for the original poster. Why should he spend a lot of more money filling is 10-gallon oil sump buying synthetic or semisynthetic oils, given the fact that 15W-40 is already the preferred viscosity for his temperatures? His small fuel-economy benefits wouldn't offset the cost of more expensive oils and he would also expose himself to more engine wear, as the manufacturer clearly recommends the highest viscosity possible.

 

[Gokhan]

Originally Posted By: Ramblejam
Originally Posted By: Gokhan
Originally Posted By: Doug Hillary
Hi,
Gokhan - The fuel saving benefits between these two viscosities occur primarily in the 30mins or so after a cold start
Your statement about fuel economy is not correct.


When comparing a 5w-40 vs. 15w-40, Mr. Hillary is absolutely correct.

First, you need to subtract the other numbers from 3.1 to get the cold-engine benefits, as it's showing the total benefits in the cold-start cycle. It still won't make much sense as it's not clear what these tests are.

Second, it's apples vs. oranges anyway. These are short bench-test cycles. In real life, the long-haul trucks spend most of their cycle with a hot engine and the cold-engine benefits become insignificant. Most fuel-economy benefits will come from the reduced HTHS viscosity. This is very well known. It's in any technical fuel-economy article and all references I posted here. The relationship between HTHS viscosity, fuel economy, and minimum oil-film thickness is one of the most basic things you should learn by reading BITOG. It's long been scientifically established ever since SAE has introduced the HTHS viscosity, as it's the most critical viscosity during an engine's normal operating coolant temperatures.

 

[Ramblejam]

Originally Posted By: Gokhan
The most relative publication in this case is the Caterpillar's oil recommendation. They say: "Generally, use the highest oil viscosity that is allowed for the ambient temperature when you start the engine." So, this is the end of story as far as the oil recommendation for this engine is concerned. Caterpillar's statement is implying that, as long as you can start the engine, a thicker oil will result in less wear.


End of story, huh?

I'm glad you brought that up, Gokhan. Apparently, in a rush to support your position, you failed to read further in that same PDF.

"SAE 10w-30 is the preferred viscosity grade for the 3116, 3126, C7, and C9 diesel engines when the ambient temperature is between -18°C (0°F) and 40°C (104°F)."

That'd be why I recommended Rotella T3 10w-30 earlier in this thread for the Seattle-based Mr. Snow.

 

[roadrunner1]

Originally Posted By: Gokhan
Originally Posted By: roadrunner1
I have yet to see any evidence of increased wear between 10w-30/15w-40.
In my own experience with UOA's I have seen LESS wear using 10w-30.

The engine manufacturer offers both grades as acceptable, so its not like we are venturing off into unknown territory with a lighter grade. The myth of needing a 40wt. in medium/heavy diesel applications is eroding fast.

For many years these engines ran for thousands of hours on straight 30wt.

Note that we're talking about heavy-duty diesel engines, not small diesel engines. I don't think you've been doing UOAs on heavy-duty diesel engines.

The following single sentence that is repeated many, many times on Pages 14 - 16 of the Caterpillar fluid reference manual[/url that was posted above summarizes what oil viscosity you should use in a heavy-duty diesel engine:

"Generally, use the highest oil viscosity that is allowed for the ambient temperature when you start the engine."

If you read those pages of the Caterpillar fluid reference manual, you'll see that they tabulate the temperatures for 0W-30, 10W-30, 5W-40, and 15W-40 grades. Then, they make the statement in that single sentence. Therefore, Caterpillar is clearly recommending 15W-40 for this engine for Seattle temperatures over 5W-40, 10W-30, or 0W-30. For me a manufacturer's oil recommendation can't be any more clear than this.


You're correct in my personal knowledge of diesel engines (UOA's) as the two largest ones I own are 8.1 & 7.6 liters, all of the rest of them are smaller.

As far as the Cat spec, the sheet I posted was the spec sheet on the OP's engine and thats where I garnered my opinion from as it states 10w-30 or 15w-40.

From my personal experience with the HEUI system 10w-30 works very well with the injection system and 15w-40 wreaks havoc with injectors during cold-starts.

As I stated above, if it were mine I would use 10w-30, UOA at 12 months and go from there as Cat states in this engines spec sheet 10w-30 or 15w-40 @ 250 hr. intervals.

 

[Ramblejam]

Originally Posted By: Gokhan
Yes, except Seattle temperatures never go that low!

That's why 15W-40 is the preferred viscosity for Seattle temperatures (greater than 10 F).


Gokhan, you obviously didn't fully read the PDF and are grasping at straws.

Caterpillar clearly states that when it's between 0°F and 104°F, 10w-30 is the viscosity to be selected for this particular engine. If operating conditions fall outside of those temperatures, then a different (be it lighter, or thicker) engine oil should be selected.

As aforementioned, Mr. Snow is Seattle based, and operates primarily in the same climate. As such, the 10w-30 preferred viscosity applies to him. This is in exception to the "Table 6" chart, and supersedes any recommendation in it.

 

[Gokhan]

Originally Posted By: Ramblejam
Originally Posted By: Gokhan
Yes, except Seattle temperatures never go that low!

That's why 15W-40 is the preferred viscosity for Seattle temperatures (greater than 10 F).


Gokhan, you obviously didn't fully read the PDF and are grasping at straws.

Caterpillar clearly states that when it's between 0°F and 104°F, 10w-30 is the viscosity to be selected for this particular engine. If operating conditions fall outside of those temperatures, then a different (be it lighter, or thicker) engine oil should be selected.

As aforementioned, Mr. Snow is Seattle based, and operates primarily in the same climate. As such, the 10w-30 preferred viscosity applies to him. This is in exception to the "Table 6" chart, and supersedes any recommendation in it.

OK, thanks for pointing out the exceptions. So, 10W-30 is the recommended oil viscosity for the Cat C9.

I wonder if they improved the design of these engines to work with smaller oil-film thickness or the 10W-30 recommendation is primarily to meet new fuel-economy requirements. I am guessing mostly the latter:

Cat C9 brochure

However, if the original poster prefers, there should be no harm in running 15W-40 in Seattle temperatures, which hardly ever go below freezing. It'll probably be cheaper overall given his typically driven mileage. People run 15W-40 even in small gasoline engines with excellent results (I've done so) and you can always run 15W-40 in a heavy-duty diesel engine as long as the cold-start temperatures are no less than 10 F or perhaps a little higher.

 

[Doug Hillary]

Hi,
Gokhan - You said this:

"It's long been scientifically established ever since SAE has introduced the HTHS viscosity, as it's the most critical viscosity during an engine's normal operating coolant temperatures"

It was the European vehicle/engine Manufacturers in forming ACEA that first placed importance on HTHS viscosity. When I first joined this Forum HTHS viscosity wasn't even discussed/understood and I was discredited for even using it as a baseline requirement in some (European) engines

The ACEA Categories simply list >3.5cP for some - especially diesel engines
There are many ?W-30 lubricants that meet this requirement!!

The API was remiss in their diesel engine specifications until the 1980s and this resulted in Manufacturer Advisory Committees being formed to address the situation. Cummins and Mack could tell a few stories from history on this subject!

The minimum HTHS viscosity for DD Series 60 engines for instance in 3.7cP - just a part of their lubricant specification

Gokhan - It may be best if you "understood" what you produce as "evidence" and don't simply discredit other's input

I've used CAT lubricant specifications as my "technical" HD lubricant baseline since around 1966. Working with Castrol and Mobil in lubricant development helps too, and of course I have hundreds of UOAs on my database that give me comfort when I dabble in such matters here on BITOG

 

[yucca]

Gokhan,
Most new cat diesel engines have been shipping out with 10w30 for several years now.

The Chevron Delo 400 LE 15w40 would easily meet the OP's needs of a 10,000 mile OCI. At a very nice price point as well.

 

[Gokhan]

Originally Posted By: Doug Hillary
Hi,
Gokhan - You said this:

"It's long been scientifically established ever since SAE has introduced the HTHS viscosity, as it's the most critical viscosity during an engine's normal operating coolant temperatures"

It was the European vehicle/engine Manufacturers in forming ACEA that first placed importance on HTHS viscosity. When I first joined this Forum HTHS viscosity wasn't even discussed/understood and I was discredited for even using it as a baseline requirement in some (European) engines

The ACEA Categories simply list >3.5cP for some - especially diesel engines
There are many ?W-30 lubricants that meet this requirement!!

The API was remiss in their diesel engine specifications until the 1980s and this resulted in Manufacturer Advisory Committees being formed to address the situation. Cummins and Mack could tell a few stories from history on this subject!

The minimum HTHS viscosity for DD Series 60 engines for instance in 3.7cP - just a part of their lubricant specification

Gokhan - It may be best if you "understood" what you produce as "evidence" and don't simply discredit other's input

I've used CAT lubricant specifications as my "technical" HD lubricant baseline since around 1966. Working with Castrol and Mobil in lubricant development helps too, and of course I have hundreds of UOAs on my database that give me comfort when I dabble in such matters here on BITOG

Hello Doug,

No, on the contrary, I appreciate you sharing with us your extensive experience very much so.

Best.

 

[Gokhan]

Originally Posted By: yucca
Gokhan,
Most new cat diesel engines have been shipping out with 10w30 for several years now.

The Chevron Delo 400 LE 15w40 would easily meet the OP's needs of a 10,000 mile OCI. At a very nice price point as well.

Yes, agreed, Chevron Delo, Mobil Delvac, or Shell Rotella 15W-40 should be more than enough for this engine for 10k-mile/1-year OCIs, and they will save money over 5W-40 or 10W-30 HDEO, given his low driven mileage not demanding the slightly more fuel economy of lower-viscosity oils.

 

[roadrunner1]

As stated in several posts earlier the HEUI system operates much more efficiently with 10w-30. Cat, along with International, joint developed this system prior to high pressure fuel systems becoming the norm.

The discussion is based around a 9 year old motorhome as Cat hasn't been supplying engines for on-road use since the EPA emissions update of '07. These engines are commonplace in many marine applications and nothing had to be "re-engineered" for 10w-30.
As I stated earlier these engines speced 30wt. for years before multi-grade oil became suitable in heavy-duty diesel engines. We used 30 wt. in everything until the mid to late 90's, the only engine that speced a 40 wt. was a silver series Detroit (6v-92) we had.

A friend of mine bought a pair of 6BT Cummins in the early 90's (marine application) and the spec sheet called for 10w-30.

 

[roadrunner1]

I am somewhat confused as how 15w-40 is going to save money over a 10w-30 as they are generally the same price????

I understand the 5w-40 aspect of your statement but the 10w-30 puzzles me.

 

[Gokhan]

Originally Posted By: roadrunner1
I am somewhat confused as how 15w-40 is going to save money over a 10w-30 as they are generally the same price????

I understand the 5w-40 aspect of your statement but the 10w-30 puzzles me.

I assumed that the original poster would consider a semisynthetic 10W-30 such as Rotella T5 10W-30, as the conventional 10W-30 HDEOs don't satisfy every manufacturer's performance requirements and they are harder to find at Wal-Mart and such. It's easier to make robust HDEO 10W-30 with some synthetic base stock because HTHS viscosity needs to be greater or equal than 3.5 cP, in contrast to 2.9 cP for PCMO 10W-30, which requires higher-viscosity-index base stocks, such as Group III or IV synthetic base stocks.

However, yes, they also make conventional 10W-30 HDEO and it would be a possibility to use such. Rotella T 10W-30 is satisfying Caterpillar ECF-2 and ECF-3 as well as Ford WSS-M2C171-E but not any other OEM spec. Rotella T5 10W-30 is satisfying every OEM spec except Mack EO-O and DDC 93K218.

 

[Gokhan]

Originally Posted By: roadrunner1
As stated in several posts earlier the HEUI system operates much more efficiently with 10w-30. Cat, along with International, joint developed this system prior to high pressure fuel systems becoming the norm.

You have a good point about the hydraulic injection system in this engine, which requires the oil to flow reasonably well for the engine to work.

For this reason, I wouldn't use 15W-40 in this engine if the temperatures go below 20 F. However, 15W-40 is certainly OK in temperatures above freezing or slightly below freezing.

 

[Garak]

Originally Posted By: Gokhan
I assumed that the original poster would consider a semisynthetic 10W-30 such as Rotella T5 10W-30, as the conventional 10W-30 HDEOs don't satisfy every manufacturer's performance requirements and they are harder to find at Wal-Mart and such.

He should be able to find a good 10w-30 HDEO sensibly priced at a distributor or perhaps even from Cat themselves. I've long given up on finding what I want at Walmart myself, so I tend not to steer people there unless there's a smoking deal.

On that note, they do sell their HDEO up here on occasion at $6 a gallon, but that's not very common.