Let’s see if we can’t stir up some more controversy within the pages of the TDR. You would not believe the correspondence created by the “Lube Oil as a Commodity” article that industry expert John Martin authored in the last issue of the magazine. I’ve often said that “discussing lube oil is like discussing religion—you can talk until you are blue in the face, but you’re not going to change anyone’s mind.” Looks like I should have forewarned John, And I should have taken my own advice and used John’s article for my personal education.
Just so the audience is clear, the latest API lube oil specification for diesel engines is CJ-4. As Martin noted in Issue 54, unlike all previous specification revisions, the latest CJ-4 is not necessarily better than the CI+4 specification that preceded it. So, if you have an older engine, you may want to stay with CI+4. Engines manufactured after 1/1/07 require the new CJ-4 specification. Newer, yes; better, not necessarily so.
Not that my opinion would change anyone’s belief, but I now look for a lube oil that meets the specification as set forth in my Owner’s Manual. And, as much as I don’t care for Wally-world (that is Wal-Mart for those that aren’t up to date on slang), I’ve found that their in-house products meet the specification and that they do have a “low, low, everyday price.”
So, there you go. Opinions are like underarms, everyone has them; some of them stink. Don’t send in nasty-grams about my family or my mother’s attire.
The relevant article in Issue 55 promised a follow-up analysis of lube oil. The “blind sampling from the bottle” unused lube oils were purchased and evaluated. And the results are…
Whoa, partner. Before you look at the results of the oil test (or any test or article written for your consideration) one has to wonder if there is an agenda hidden behind the data. The college professor that taught the statistics class was fond of saying, “figures don’t lie, but liars figure.” Is I have a hidden agenda here?
Most assuredly, no. I have several friends in the lube oil manufacturing and retailing business. The TDR has lube oil advertisers. I cheer for race teams with lube oil sponsorship and livery emblazoned on the side of the race car. Lube oil companies sponsor many of the diesel drag race and diesel sled pull competitions in which the TDR audience participates.
So, let’s take a minute to revisit and add to the comments I made in Issue 55. “When new lube oil is analyzed you can get a good idea viscosity at higher temperatures, maintaining high alkalinity and protecting against wear with the right blend of molybdenum, zinc, phosphorus and boron are important lube oil attributes. Readings for calcium are a way to measure dispersion detergency.
“In the blind-sampling-from-the-bottle done by Trailer Life magazine in January 2005, I was greatly disappointed to see that Wal-Mart Super Tech 15W40 diesel oil stood toe-to-toe with other very respected brand names.
“Why disappointment? First, consider what John Martin said, ‘Consequently there is less and less difference between engine oil that barely passes the API certification test and one that is designed to pass by a significant margin. Therefore, oils meeting a given performance spec (example API CI-4+) are approaching commodity status.
“Second, I am not a big fan of Wal-Mart. I could go into a long tirade, but I will refrain.
“Third, for all of my vehicle ownership years (let’s see, that is about 36 years) had I been duped? Had I fallen for the marketing hype? Or, as we know, the focus on lube oil base stock versus the importance of the additive package changed over the years. Is this a good excuse? I do not want to believe that lube oil is just a commodity. Yet the Trailer Life grid did not lie.”
Your thoughts? How about this, “Well, Mister Editor, you’ve established that the test is unbiased. But, if you are not going to change what a person believes, why bother?”
Good observation and question. The answer, “I’ll spend the money on lube oils and analysis so that John Martin and I can have data to debate and discuss. If by chance should the data might enlighten and educate others, then so be it.”
Blind Sampling - Figures Don't Lie
Presenting the blind-sampling-from-the-bottle data.
Notice that I listed the lube oils by number. Thus there is no bias. Did you pick a favorite?
The Price Factor
Now let’s consider price. The price reflects the cost per gallon.
Is your selection of a favorite oil influenced by price? Now, I’ll turn the article over to John Martin for his analysis of the lube oil data.
JOHN MARTIN'S RESPONSE
Obviously the editor is trying to trick me by sending me the oil analyses and asking me to determine which is the best oil for my engine (and yours). Now, the data sent doesn’t have Nitrogen (N) levels, so I can’t judge relative dispersant content of the oils. That’s okay, I wouldn’t worry too much about dispersant content unless I were running a lot of stop-and-go service. Engines with frequent speed changes (particularly in colder climates or before the engine is fully warmed up) need the most dispersancy to prevent sludge buildup. Most modern diesel engines have plenty of dispersancy, so let’s not loose any sleep over that.
What about detergency? I don’t know if I’ve said it in TDR before but, “Diesels love detergents!” The only reason more detergent isn’t placed in the oil is that: (1) high detergent oils have a tough time passing the passenger car tests which are part of the tests required to put the API donut on the can; (2) high detergent content oils can sometimes interfere with the additives responsible for valve train wear protection; and (3) high detergent oils allegedly can prematurely plug particulate traps. Item (1) ensures that you can put your diesel oil in your passenger vehicle without damaging it. Here’s a dime—call someone who cares. Either this is a leftover concern from years ago or a concern about selling to ill-informed customers; I’m not even sure it’s still relevant with today’s oils. Do you use the same oil in both your cars and your trucks?
Item (2) was a little more relevant when oils didn’t have the wear protection they have today, but prior to electronic fuel injection those diesels had tremendous valve train loading on the fuel injector pushrods. As a result oils formulated for modern diesels have to have very good EP (extreme pressure) protection to prevent premature fue injector pushrod tip wear. That’s why, at least up until the API CJ-4 specification, diesel oils have had more zinc (zincdithiophosphate) than passenger car oils. There is a concern with passenger car oils about the effects of high zinc and phosphorous levels on catalytic converter life. One of my beefs with API CJ-4 oils is that limits have now been placed on zinc and phosphorous to prevent premature particulate trap plugging.
Another of my beefs with the API CJ-4 specification is that it places a limit on the amount of detergent in the oil in the name of preventing premature particulate trap plugging. I’ve not seen any compelling data to support this claim. Could it be that our major international oil marketers decided that oils containing less purchased additives might make them more money in the long run? We all know that the poor oil companies are just barely making a living!
Okay, I’ll get off my soap box and examine the data.
My first observation is that oil 3 is unique. It uses a combination of calcium and magnesium detergents, and it has a relatively lower level of zinc and phosphorus than the other oils. This oil is a product of what we in the industry refer to as the “Double Cross Oil Company’s” additive division (Exxon/Mobil). Magnesium is preferred by those who want to pass laboratory engine tests, but field test results tend to favor the use of all calcium detergent systems for diesel trucks. Besides, magnesium and water don’t get along. Note that all of the other diesel engine oils have a calcium only system. (Ignore magnesium levels below 15 parts per million (PPM) because that is at the low end of the detection systems used to analyze oils.)
Also look at the total amount of detergency. Oil 3 has 2300 PPM detergent. Now look at the total base number (TBN) of 8.99 units. Oil 3 has the lowest detergent content of all the oils tested. In terms of fully warmed-up field test performance, it is probably the lowest quality oil here. However, I’ll also bet that it is an API CJ-4 or an API CI-4 plus oil judging by the relatively high TBN value for the detergent content. I would guess this oil would contain a lot of dispersant to pass the latest tests, but do you need it? I don’t think so!
Oil 4 has the second lowest detergent content of the oils tested (2500 PPM calcium) and the lowest TBN. (Be careful when comparing TBN values, repeatability is on the order of + or – 0.5 units.) But again it has a relatively high TBN for the detergent content, so I’m guessing that it is a CJ-4. It has marginally higher levels of zinc, but not quite as high as the other oils. I personally wouldn’t cross the street for a free crankcase of oils 3 or 4 unless I were running a fleet of buses or garbage trucks.
Oils 5, 6, and 7 are middle-of-the-road oils. Not great, but not bad either. There are tons of these types of diesel oils out there, and they do a perfectly good job of lubricating your diesel engine. I imagine these oils are all API CI-4 oils, and suspect that they are okay for your engine. If you’re looking at price versus performance, oil 5 is hard to ignore, because it only costs $7.68 per gallon.
Oil 2 looks marginally better than oils 5, 6, and 7, and at a price which is competitive with oils 6 and 7. I think this is probably a good upper mid-range performer. I also like the fact that it includes boron (probably a borated dispersant or a boron oxidation inhibitor).
However, my two favorites are oils 1 and 8. Both of these oils contain a slug of calcium detergent and sufficient phosphorus and zinc to protect the valve train. Oil 1 also appears to use a borated dispersant or boron containing oxidation inhibitor, so that is a definite plus. If price is part of your equation, you should select oil 1. Due to the much higher price, I would suspect that oil 8 is at least a partial synthetic. (Remember, there is nothing magic about synthetic oils unless you need ultra high or low temperature protection.) I like oil 8, but I’m not sure I would pay the cost difference over oil 1.
Well, I hope I’ve thoroughly confused everyone by now. As you can see, oil chemistry is very complicated; but if you learn a little something about reading oil analyses, you won’t be misled nearly as often. Robert asked me if I could tell which oil was manufactured by which company—As I said in Issue 55, oil chemistry between competitors is becoming more similar all the time. That’s why I think oil is becoming more of a commodity with each new specification. To me it’s obvious that oil 3 is ExxonMobil. From Robert’s earlier comments about Wally World oil, I can conclude that oil 5 is probably WalMart (which, of course, would be manufactured by someone else). But, from there on out, even I can’t tell one brand from another. I wouldn’t worry about the performance of any of them in your vehicle’s diesel engine.
(Intentionally left blank—you’ll have to draw your own.)
|Cummins (Valvoline) Premium Blue||CI-4 plus|
|NAPA Universal Fleet Plus||CI-4|
|Mobil Delvac 1300 Super||CI-4 plus|
|Shell Rotella T||CJ-4|
|WalMart Super Tech Universal||CI-4|
|Castrol GTX Diesel||CI-4|
|Motorcraft Super Duty||CI-4 plus|
|Shell Rotella T Synthetic (5W40)||CI-4 plus|
Did you not see your favorite oil tested? Those that were included in the survey were collected from four auto parts and discount warehouse locations. For TDR Issue 57 we will add several of the popular mail-order lube oils and several semi-synthetic blend lube oils to the survey. With the additional data you’ll be able to compare, contrast and price-factor a wider range of products. Until next time…