"Engine oil viscosity has VIRTUALLY NO EFFECT ON WEAR."

[TallPaul]

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Originally posted by TallPaul:
The accompanying chart shows a "typical" straight 30 having higher effective viscosity under high sheer than a "typical" 20w50. The chart also indicates this high sheer rate that may be happening in the bearing is much higher than the sheer rate at which the test was run.

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Well I don't think the referenced "standard test method" was HTHS as we know it (no date on chart, but the Tribology book it's in dates from 1993). The chart, actually graph, shows the 20w50 dropping below the straight 30 at 10,000 s-1 sheer rate at 20C, and at 100,000 s-1 sheer rate at 100C (typical mineral oil in both cases). On the other hand, Mr. Fitch's "How to select an oil ..." book defines HTHS as typically measured at 1 million s-1 sheer and 150C.

Anyway, Callisa seems to be onto someting. As I recall, he is with the oil industry in Germany. Posts a lot at Noria.

 

[SteveT]

Newbie here, I have been visitng BITOG for several months and have learned a lot. As the owner of a 04 F150 I've been very interested in the 5w-20 oil issue. I was convinced the 5w-20 was fine until I started reading about the HTHS. As I understand it this is a measure of an oils viscosity under high temperature and pressure conditions in critical engine areas. This has raised a question in my mind. Is it valid to directly compare HTHS numbers of different weights of oil? The HTHS is measured at the same temperature for all weights of oil, however, as I understand it a thinner oil runs cooler due to lower friction, and it should flow faster through the bearings and valve train, further reducing the peak temperatures it experiences. So should a thinner oil be "allowed" a lower HTHS since it won't get as hot?

 

[moribundman]

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You don't have to have an A3 rated oil in all engines.

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You know exactly that I never said that.

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Is Mobil 1 R A3 rated or 0w-20? Nope.

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What's your point?

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Mobil 1 0w-40 is A3 rated. Doesn't seem to offer any benefit over Mobil 1 5w30 A1 rated in most modern engines.

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"seem" "most"

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If your car calls for an A3 rated oil, then use one.

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No, my car calls for an oil spec required by the carmaker. And you bet I choose an oil that meets at least three of the most basic and important specs contained within the requirements:

1. allowed viscosity range, for example 5W-40 or 10W-60

2. minimum HTHS 3.5

3. maximum sulfated ash content 1.5%


In case you still haven't understood, my issue isn't with you saying that not all engines require a "high" HTHS, but that you keep making generalizations that might make some guy put an oil with HTHS 2.9 in his $90k toy.

You have been routinely ignoring and dismissing the posts that showed how wear increased considerably if the HTHS fell under 2.9, while wear decreased with increasing HTHS, up to about HTHS 4. And yes, it's engine specific! Just stop making generalizations, because they mean absolutely nothing.

 

[buster]

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What's your point?

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I'm not making generalizations, I'm QUESTIONING the importance of HT/HS. For one thing, a well built oil with a strong additive package would probably do fine. Molekule has stated before that modern engines could run on an oil as think as a 4cSt oil. What do you think the HT/HS would be for that? And their is a relationship between HT/HS with it GENERALLY being that the thicker the oil the higher the HT/HS, but not entirely linear. It plateaus at around 40wt.

GC is 12.3 or whatever cSt and has a HT/HS of 3.6. Amsoil 0w30 is 11.2 cst and has a HT/HS of 3.4. Mobil 1 R is 10 cSt and has a HT/HS of 3.0. So it does follow viscosity to some degree. RL's 5w-20 has more ester so it's going to be more shear stable.

quote:

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You have been routinely ignoring and dismissing the posts that showed how wear increased considerably if the HTHS fell under 2.9, while wear decreased with increasing HTHS, up to about HTHS 4

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I have not ignored it. That was ONE study done on ONE engine type. It is interesting to note that some of these lower viscosity oils, such as the xw-20's are performing as well or better in some instances then oils with higher HT/HS numbers.

I agree though that if your car calls for an A3 rated oil, you should use one. It's obviously designed for that type of oil.

[ January 22, 2005, 07:10 PM: Message edited by: buster ]

 

[Patman]

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Originally posted by buster:

quote:

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The lack of observation is not proof of anything

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Never said it was. Read again.

The most over rated, over hyped spec talked about on this board has been ACEA A3. Most if not all X-40wt oils carry the A3 approval. Most if not all 40wt oils, do not provide better protection then 30wt A1 oils. You don't have to have an A3 rated oil in all engines. Is Mobil 1 R A3 rated or 0w-20? Nope. Mobil 1 0w-40 is A3 rated. Doesn't seem to offer any benefit over Mobil 1 5w30 A1 rated in most modern engines. If your car calls for an A3 rated oil, then use one.

And where are all these Corvettes and Vipers with Engine failures running on Mobil 1 A1 5w/10w-30? A 10 cSt oil as well.

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Two points I'd like to make here.

1. Most Corvette owners don't drive more than 5 or 6k per year, so no matter what oil they choose they'll probably never wear out their engine.

2. There are a significant number of LS1 Corvette (and f-body) owners who burn a good amount of oil when using the thin Mobil 1 5w30. A lot of these guys come to me for advice and when they take my advice and switch to something closer to a thick 30/thin 40wt, they see their oil consumption go down considerably.

 

[pscholte]

quote:

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Originally posted by Terry:
Which vis; dynamic, kinematic ?

Which fluids Newtonian,plastic,dilantant,pseudoplastic,
thixotropic ?TD

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I am talking pseudoflambic viscosity and am dealing with Hawaiiantropic fluids. I can't seem to find a suitable test...the only one that approaches any logical results is the Waikikic test performed by Bruddah Fungo Kamakwiwo'ole in a liddo shop Diamond Head side, slightly mauka.

 

[buster]

Patman, try and get someone to run Redline 5w-20 in the LS1. I'd love to see a used oil analysis on that.

 

[JohnBrowning]

buster, As much as I like you I have to ask you to do something for me. Look at your results with your Carolla and post the HTHS of the oils you think did the best in that car for both excellent UOA and oil consuption for me. I think you will find that the oils that did best all had HTHS numbers higher or equal then 3!I think you will find that SAE viscosity does not correlate as closely with the wear numbers as the HTHS does!


No one is saying that an HTHS of 5 is going to give you better protection then an HTHS of 3.5. What is being said is that HTHS corelates closely with wear and increaseing HTHS will reduce your wear up to a point. IT is a clasic case of marginal returns. At some point your return for increase HTHS will deminsh as compared to the cost of doing so.

The problem is that the load on the parts and bearing clearance are closer to constant then the oil recomendation made by manufatures. You can only decrease clearance so much and all manufactures preety much have access to the same bearing technology. To add to this confushion you have multiple recomendation based on what country the engine is going to even with identical engines. The same is true for cam loading. You can only play around with spring tension and cam profiles so much and still be competive with power,NVH,durability and emmissions.

 

[buster]

quote:

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What is being said is that HTHS corelates closely with wear and increaseing HTHS will reduce your wear up to a point. IT is a clasic case of marginal returns. At some point your return for increase HTHS will deminsh as compared to the cost of doing so.

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John I do agree with you to some point. I know what your saying and it makes sense. What I'm saying is that if you take an thin 30wt oil or 20wt, such as Mobil 1 5w-20 and Mobil 1 R , which have a HT/HS of only 2.8 to 3.00, BUT, has a strong additive package, wouldn't that offset the shear aspect?

In Mobil 1R's case, and also the 76 racing oil, it's probably designed to shear a bit, pick a few HP, but still protect well due to it's higher additive content. And like you said, depending on the engine design, in terms of bearing clearances, that would change the equation as well.

Also, take Mobil 1 10w30 and Amsoil 10w-40. Now this is an apples to oragnes comparion but I have no doubt that Mobil 1 10w30 will most likely shear LESS in most engines with it's 3.2 HT/HS compared to Amsoil's 10w-40 3.9 HT/HS. We've seen this all the time. Some of these 0w30 oils thin down, but might have a higher HT/HS then Mobil 1 10w30, which NEVER shears down at all.

 

[Ugly3]

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Originally posted by G-Man II:

quote:

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Originally posted by Ugly3:
I guess I failed to make my point well enough. If the iron ppm were 17 on one used oil analysis and 71 ppm on another used oil analysis from the same engine how do we know the ppm numbers relate to actual ware in the engine? I have seen no data to corrolate ppm in a used oil analysis to actual engine wear.

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Where do you think the metals in a used oil analysis are coming from if not from wear?

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Ya see, this is exactly my problem. Everyone assumes that metal ppm in a used oil analysis means engine wear. Maybe it means one oil suspends particles better than another, I don't know. But what I do know is that I have not seen any information that relates ppm in a used oil analysis to actual wear.

Let me ask your question backwards. Where are the wear metals going in the Paradise Garage study where the wear metals stay about the same for 1000's and 1000's of miles, is there no additional wear? I doubt it.

 

[buster]

quote:

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The accompanying chart shows a "typical" straight 30 having higher effective viscosity under high sheer than a "typical" 20w50. The chart also indicates this high sheer rate that may be happening in the bearing is much higher than the sheer rate at which the test was run.

So I am wondering if the "standard test method" is HTHS and then that parameter is not as reliable as we may have thought. And different engines and/or conditions of the bearing may have bearings that are harder or easier on oil.

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This is an excellent question, and just another example of how little we really know about these numbers we look at and compare. For instance, why does Mobil 1 0w-20 do so well even under high stress? Why is the Mobil 1 R and 76 Racing oil formulated with a HT/HS of only 3.00? Like some have said above, you have to take the engine your dealing with and let analysis speak. But it's clearly not a "black and white" issue in thinking that having a higher HT/HS means you will have a better oil.

[ January 22, 2005, 12:09 PM: Message edited by: buster ]

 

[Motorbike]

From the Lube Engineers perspective read the 3rd and fourth posts here .

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000081

 

[Motorbike]

TallPaul

Can you recall anything Jim Fitch has written concerning the topic ? If so , please post .

 

[JohnBrowning]

buster, AW is a bandaid for hydrodynamic failure! It is a good thing to have some AW additives but it is bad to try to make up for a weak bsestock with additives! It is like trying to make up for a bad diet with synthetic vitimins! Vitimins and minerals are great but are even better in their whole food form!

Terry, I understand that I do not need to have a liquid plastic!! LOL!! I guess the Boy Scout in my just wants to "Be Prepared"! My father always taught me things like "The mission always comes first!", "Prepare for the worst case and hope for the best!", "You can't should have a problem.", "Their is no such thing as overkill if you make it home.", "Chance favors the prepared.","An once of prevention is worth a pound of cure!"etc.........

It is hard to go wrong useing an oil with at least an HTHS of 3.2-3.5! You can find oils from 5W20's to 0W40's that fit this.

I am useing an oil that violates my rules and only has an HTHS of 2.99 but I am hopeing that the AW additives will make up for this short term. We will see!

[ January 23, 2005, 01:18 AM: Message edited by: JohnBrowning ]

 

[G-MAN]

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Originally posted by Ugly3:
Ya see, this is exactly my problem. Everyone assumes that metal ppm in a used oil analysis means engine wear. Maybe it means one oil suspends particles better than another, I don't know. But what I do know is that I have not seen any information that relates ppm in a used oil analysis to actual wear.

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You still seem to be missing the obvious: Even if the oil suspends the particles better than another, THE PARTICLES HAVE TO COME FROM SOMEWHERE, and they come from wear.

quote:

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Originally posted by Ugly3:
Let me ask your question backwards. Where are the wear metals going in the Paradise Garage study where the wear metals stay about the same for 1000's and 1000's of miles, is there no additional wear? I doubt it.

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Huh? The wear metals don't "stay the same" for thousands of miles. The wear RATE as evidenced by the wear metals may stay the same, but the ppm of wear metals is cumulative, indicating cumulative wear inside the engine. In other words if I have three consecutive used oil analysis and each one shows 5ppm of iron, then my total iron "wear" over those three used oil analysis is 15ppm.

 

[Ugly3]

G Man II - Huh? The wear metals don't "stay the same" for thousands of miles. The wear RATE as evidenced by the wear metals may stay the same, but the ppm of wear metals is cumulative, indicating cumulative wear inside the engine. In other words if I have three consecutive used oil analysis and each one shows 5ppm of iron, then my total iron "wear" over those three used oil analysis is 15ppm.

I'm sorry, I again have not been clear enough. In the Paradise Garage study there are 1000 miles used oil analysis on the same oil and filter for 14,000 miles with Amsoil. At 10,000, 11,000, 12,000, and 13,000 miles the numbers for copper were 60, 66, 57, and 65. The numbers for Iron were 16, 17, 17, 19. The numbers for alum were 3, 4, 4, 4.

The ppm suggest virtually no wear for the 4000 mile run. I really doubt there was little to no wear going on.

 

[TooSlick]

Ulgy3,

You have to keep in mind that some fresh oil was added during those 4000 miles, which tends to reduce the wear metal concentrations. So there was some wear taking place, even if it was at a very low rate.

The most interesting thing to me about the 3MP testing is that the highest rate of wear appeared to take place during the first 3000 miles. This indicates that changing oil disturbed the AW additive film that has developed and it takes several thousand miles to fully reform it. Perhaps a negative to frequent oil changes, at least in terms of valvetrain wear.

TS
Dixie Synthetics

 

[Shannow]

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Originally posted by JohnBrowning:
buster, AW is a bandaid for hydrodynamic failure!

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That's pretty much waht we were taught in bearing design.

Anti-wear is good, but as a back-up to hydrodynamic lubrication.

 

[Shannow]

Tooslick,
I often wonder whether that initial rise in "wear" metals is due to solubility, and trying to establish an equilibrium.

Maybe (purely my contemplation, not backed with anything), the oil starts to dissolve metals from the engine, until a point of equilibrium is reached.

Would explain why oil is so "hungry" until it gets some metals into it.

Just an idea.

 

[wulimaster]

quote:

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Originally posted by TooSlick:
Ulgy3,

You have to keep in mind that some fresh oil was added during those 4000 miles, which tends to reduce the wear metal concentrations.
The most interesting thing to me about the 3MP testing is that the highest rate of wear appeared to take place during the first 3000 miles. This indicates that changing oil disturbed the AW additive film that has developed and it takes several thousand miles to fully reform it.
TS
Dixie Synthetics

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I agree with the oil loss (4 oz/1k miles for analysis and topoff loss) and additional oil added would account for this drop as well as a possible lab error or change in oil sample retrieval method or retrieval time after shutdown.

My best guess for the large particulate count in the 1st 1000k mile sample is probably due to the esters polarity keeping much of the esters clinging to the inside of the engine after the oil change. Also, the esters hold the add pack which includes the additives responsible for holding the particulates in suspension. That is why I advocate looking at the 1k sample as the baseline and not the virgin sample.

As for the wear count per 1k dropping with each succesive analysis, that could be due to the thickening of the oil which might ( I say might) be causing an increase in the HT/HS.