Viscosity Has No Effect on Wear?

[nick778]

The following link is to a Blackstone Labs Newsletter. The author at Backstone asserts there is no correlation in wear and viscostiy. He asserts that wear is a function of keeping the oil clean (and I would guess changed often). What do you think? Based on the UOAs done by them and posted here, I would tend to disagree on such a blanket statement.

blackstone newsletter

 

[pscholte]

I suggest you watch the UOAs coming in from 5W20 users...my guess is that the results you will see will challenge your thinking if you uncategorically relate "thick" to reduced wear.

[ February 01, 2004, 07:19 PM: Message edited by: pscholte ]

 

[jthorner]

It seems that the notion of thicker oils providing lower wear is a worn out old rule of thumb and does not really apply in the current world. Quality is more important than size

.

John

 

[tpi]

http://www.tytlabs.co.jp/office/elibrary/ereview/rev324epdf/e324ab_tohyama.html

5W20 HTHS viscosity is somehere about 2.6. According to charts I've seen this is the start of a low wear plateau compared to even thinner oils. Still HTHS viscosity of about 4 showed approx 20% lower main bearing wear on a test chart posted somewhere on this site.

Concerns me that the HTHS viscosity is rated at 300 degrees F, which is supposed to represent the hottest temperature found in engine. Somehow I suspect this isn't the case. On a very hot day, I've seen sump temps in the 250 degree range and I suspect others have seen higher. Obviously your peak internal temps would be higher than 300 degrees under these conditons.

I'm sure viscosity is over rated as it correlates with wear and obviously the better cold flow of thinner oils are beneficial. I think common sense applies for hot weather use, long trips and the appropriate viscosity. Much evidence from manufacturers points in this direction-which has been posted on this board.

 

[medic]

#1, pscholte, glad to see you back

IMHO regarding this issue - some engines can run a thinner oil and prduce very good wear numbers, while other can't.

Recent Ford & other UOA's have shown excellent numbers with a 5w-20. Others have shown high lead with a thin 5w-30, but much lower lead with a thicker 5w-30 (Patman's LS1) and other chevy 350's. This may be due to a thicker oil, or it may be due to the different brand of oil and viscosity is totally unrelated to the decrease in lead.

I recently posted UOA's from a Ford 5.0L. The first UOA was a 5w-30 that thinned out to a high 20 wt. It had high lead levels. I blamed it on the thinning of the oil. The next UOA was a different brand of 5w-30. It thinned even more, but showed much less wear in every catagory. I beleive in this case, the viscosity had nothing to do with wear, but the additive package was the difference in the wear. Keep in mind that this is an engine that Ford recommends a 5w-20 in.

TooSlicks recent UOA with a 5w-20 in an engine that calls for a 5w-30 wasn't so good. Once again, was it due to viscosity or different oil?

[ February 01, 2004, 08:40 PM: Message edited by: medic ]

 

[buster]

quote:

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Based on the UOAs done by them and posted here, I would tend to disagree on such a blanket statement.

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Depends on the engine and the oil. A 20wt in a LS1? Nope. A 20wt in a Ford V8? Yep. Works. All depends. I agree over all with the statement. Not too mention Terry, Molekule and TS do as well.

 

[pscholte]

Thanks, Medic.

I think one of the underlying currents on this board, and it probably relates to the experience we have had with auto dealers, is that "you just can't trust the auto company recommendations." I know that I have been guilty of an "I think I know better what will make my car last" attitude. I have come to this conclusion: while it is VERY true that many dealers don't fill us with confidence as to their integrity or their technical acumen, I believe the company engineers DO know what they are doing and we can apply their recommendations--viscosity, for example--with confidence. SO, if an engine manufacturer says this SAE rating and viscosity will give us good service and longeivity in their engines, I think we can rest confident in that, but we should not apply one manufacturer's recommendations to someone else's products. So where does that leave us....You are right, Medic; once the approved oil specs are applied, it comes down to the additive package.

 

[XS650]

quote:

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Originally posted by pscholte:
I believe the company engineers DO know what they are doing and we can apply their recommendations--viscosity, for example--with confidence.

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I also believe they know what they are doing and would be glad to use what they use in their personal vehicles when they aren't being pressured by corporate to meet Federal economy requirements.

Unless you know for a fact that the oil or other maintenace recommended is in fact what the engineers would recommend without their arms being twisted, then you are still guessing what's best for your application.

****

 

[pscholte]

Well, ****, that leaves us with three choices; (1) believe the engineers are NOT having their arms twisted and accepting what they put in the owner's manual; (2) believe that they are, but that "twisted" advice is better than what we can come up with as amateurs (our chemist/engineer board members excepted); or (3) make our own amateurish best guess...I'll go with "(1 1/2)."

 

[Jay]

I read the article and I think I understand what the author was trying to say:

quote:

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...The oil's ability to act like a solid and protect parts is not related to its thickness...

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This is true for elastohydrodynamic (EHD) films. In this type of film, increasing oil pressure increases the viscosity of the oil till it becomes very hard--sometimes harder than the metal surface it protects. EHD films protect gears and ball-bearing races. The author gave a gearbox as an example for his point.

Hydrodynamic films are much thicker and depend on viscosity (and motion between moving parts) to form, so viscosity is important for moving surfaces that need hydrodynamic films.

 

[heyjay]

quote:

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Originally posted by tpi:
http://www.tytlabs.co.jp/office/elibrary/ereview/rev324epdf/e324ab_tohyama.html

5W20 HTHS viscosity is somehere about 2.6. According to charts I've seen this is the start of a low wear plateau compared to even thinner oils. Still HTHS viscosity of about 4 showed approx 20% lower main bearing wear on a test chart posted somewhere on this site.

Concerns me that the HTHS viscosity is rated at 300 degrees F, which is supposed to represent the hottest temperature found in engine. Somehow I suspect this isn't the case. On a very hot day, I've seen sump temps in the 250 degree range and I suspect others have seen higher. Obviously your peak internal temps would be higher than 300 degrees under these conditons.

I'm sure viscosity is over rated as it correlates with wear and obviously the better cold flow of thinner oils are beneficial. I think common sense applies for hot weather use, long trips and the appropriate viscosity. Much evidence from manufacturers points in this direction-which has been posted on this board.

---

Nice link it's interesting to see how "other" engineers interpret or explain their results.

Your concern on the HTHS run at "only" 150 C is a valid one. According to tests run by Esso Canada on representative Cat and Cummins turbocharged HD diesel motors, the oil film next to the rings will exceed 600 F.

Still, that's all we have to go on, unless you can find oils that rate NOAK volitility at those high temps, otherwise known as "distillation point."

The "old" Mobil Delvac 1 5W-40 used to be rated around 3% distillation at 700 F.

Jerry

 

[medic]

I agree that the people who engineered the engine usually know what will work the best. Once again, I'll bring up Ford and Honda's 5w-20's. These work great in the engines that the manufacturers say they will.

One bad choice by GM engineers - Mobil1 5w-30 in an LS1. This engine has shown to like a thicker oil. I would assume that a GM public realtions specialist accompanied by an Exxon/Mobil representative decided that Mobil1 5w-30 would be a great sales pitch for both companies.

The engineers just chose a API SL 5w-30.

GM - "our high performance engine is so powerfull that it needs a quality synthetic oil"

Exxon/Mobil - "our Mobil1 line is chosen as a top notch oil by one (or more) of America's largest automotive manufacturers"

Mobil1, being one of the few readily available, over the counter, synthetic oils, not to mention probably one of the most recognized synthetic oils, obviously fits the bill for any automotive manufacturer in need of a synthetic fill for their vehicles.

[ February 01, 2004, 10:58 PM: Message edited by: medic ]

 

[outrun]

Hmmm...does this Vindicate Royal Purple?

 

[moribundman]

Yup, there can't be any relation between increased wear and high viscosity oils. That many of the latest motors in Europe wear out faster than they did ten years ago has surely absolutely nothing to do with the steadily increasing use of low HTHS oils and extended drain intervals of up to 30k km (or whatever it is now), just like it has nothing to do with the latest engine designs. And nobody is now afraid to buy a diesel if it has more than 200k km on it either, right?

Please take note of the use of sarcasm, and take what I just said with a grain of salt, but at least consider sticking with the engine maker's recommendations regarding the type of oil used for a particular engine. Also, see this recommendation in context of the driving habits of the average owner of said car.

You just can't make categorical statements like "thin oil" will cause increased wear, but at the same time you cannot claim that "thin oil" will not cause inreased wear in engines that are not designed for those oils.

In conclusion: Viscosity has no noticeable effect on wear as long as an oil can keep moving metal parts seperated.

[ February 01, 2004, 11:53 PM: Message edited by: moribundman ]

 

[buster]

quote:

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In conclusion: Viscosity has no noticeable effect on wear as long as an oil can keep moving metal parts seperated.

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Well said.

 

[Bio-T]

quote:

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Originally posted by outrun:
Hmmm...does this Vindicate Royal Purple?

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I think the 15W40 Royal Purple oil is one of the best on the market for price. Many of my friends run it with great analysis. I have no problem recommending or using this oil in any weight. Now I am only talking about their API certified oils, not the Race oils. And with their Dexron III/Mercon trans fluid and Diff. fluids, all synthetic, my truck engine should outlast the body sheet metal.

 

[JohnBrowning]

Well obviously I do not have the data set to make a statement refureing them. I would like to point out how poorly two different brands of 5W20/0W20 oils performed in Tooslicks truck. I would also like to point out how people on this site that have tried 15W40,20W50 and 15W50 oils have seen improvments in UOA and consumption. Off the top of my head we have a recent Cadilac posting this and we have ToyotanSaturn that also had good results going this route! Patmans car likes thicker 30Wt. oil wich means it would probably love a synthetic 5W40! 59Vettman has vouched for RP 15W40 as turning in good number!

No mater how you slice it the lower the HTHS the greater the chance of hydrodynamic failure. This is especily true when the HTHS drops below 2.9! Now does this mean that you will always have high wear when HTHS drops below 2.9??? NO!! THe problem is that once you reach the bottom limit their is no saftey margin. You never know when you might get a partial system failure like coolant leak, belt slipage, water pump failure,detonation, sudden heavy shock loading etc........I preffer to be prefared for catatrophic failure like bearing hemorageing oil etc.....

Haveing an HTHS higher the 2.6 or2.9 is only helpfull when it is needed kind of like extra oil capacity or a surplus of engine torque!

I also do not think any one has demonstrated that their Ford or Honda has had greater wear with 10W30 then with OW20 or 5W20 from the same manufacture like compareing M1 0W20 to M1 10W30!

I am still waiting for someone to run 5W20 or 0W20 in an LT1,LS1 or any Gen I,II,III block. I bet busters Carola would eat 0W20 like crazy! I doubt that Patman would run a 5W20 in his F-Body! I doubt Pablo could be convinced to try it in his Turbo Volvo's! How about Dr.T in his Mercedes? Terry and MolaKule really have not chimed in on the 20Wt. issues as far as I am aware! If diesel fleets thought that they could save 1% or more on fuel costs by switching over to XW20 oils without destroying the engines they would do it in a made minute!

 

[Last_Z]

quote:

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Originally posted by pscholte:
I suggest you watch the UOAs coming in from 5W20 users...my guess is that the results you will see will challenge your thinking if you uncategorically relate "thick" to reduced wear.

---

Read nick's last two words...."blanket statement." I agree with him, XW-20 oils ARE NOT designed for all vehicles and if used in the wrong application, one could pay dearly for the mistake.
I do believe that if used in the appropiate vehicle, many times going thicker will not improve wear.

Rick

 

[DavoNF]

quote:

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Originally posted by medic:
I recently posted UOA's from a Ford 5.0L. The first UOA was a 5w-30 that thinned out to a high 20 wt. It had high lead levels. I blamed it on the thinning of the oil. The next UOA was a different brand of 5w-30. It thinned even more, but showed much less wear in every catagory. I beleive in this case, the viscosity had nothing to do with wear, but the additive package was the difference in the wear. Keep in mind that this is an engine that Ford recommends a 5w-20 in.

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If there is no "arm twisting" going on, why does this exact same engine, manufactured in USA, require a 15W-40 in Australia? I have a 5.0L Ford and the owners manual and workshop manual both quote this as the recommended viscosity.

We have no CAFE requirements here.


Dave

 

[XS650]

quote:

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Originally posted by pscholte:
Well, ****, that leaves us with three choices; (1) believe the engineers are NOT having their arms twisted and accepting what they put in the owner's manual; (2) believe that they are, but that "twisted" advice is better than what we can come up with as amateurs (our chemist/engineer board members excepted); or (3) make our own amateurish best guess...I'll go with "(1 1/2)."

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Since I was an engineer for quite awhile, and even managed a powertrain group, I know that as a general rule #1 isn't a valid assumption.

If you believe the engineers that design things have final say on what goes in the owners manuals and shop manuals, I own a large golden colored bridge just north of San Francisco I'll sell you.

When you decide to slavishly follow the owners manual, you are slavishly following the corporate party line, which may or may not be what is best for you. And may or may not be what the people that designed and tested the stuff use in their own cars.

I found out about 15W-40 diesel oil being good for a lot of things besides trucks from a GM powertrain engineer in the 1980s.

You can take #2 and think for your self a bit. Consider what the corporate objectives are and how they would have affected the published recomendations we get in our owners manuals.

Also consider what happens if the oil you but is at the extreme ends of it's viscopsity rating. A 20 weight can be nearly the same as thin 30 weight, or a thick 10 weight.

I know what I'm going to run. If you really believe that your owners manual was written with the objective of giving you best engine life wihout a big bias towards meeting corporate fuel economy objectives, then good luck. Check back in 200,000 miles.

I have no problem with thin lubricaants in the proper application. I have designed succesful journal bearings that used water as a lubricant. But engines aren't designed that way.