Engines that actually require Thick or Thin oil?

[OVERKILL]

Originally Posted By: PimTac
I want to know how a member can add to their post without the edit notification? The part in Red was not in the original post a few minutes ago.


It's a check-box at the bottom of the screen.

 

[PimTac]

As Shannow posted, it’s no wonder some of the replies don’t add up. I’ve seen this a couple of times now and just attributed it to my old age and lacking in memory. The poster has to unclick the box so it’s a intentional act.

 

[OVERKILL]

Originally Posted By: PimTac
As Shannow posted, it’s no wonder some of the replies don’t add up. I’ve seen this a couple of times now and just attributed it to my old age and lacking in memory. The poster has to unclick the box so it’s a intentional act.


I do it sometimes when I've made a spelling or grammatical error, which I think is the primary purpose for its existence.

 

[Shannow]

Originally Posted By: ZeeOSix
Yes, a cherry pick ... but you can find these similar graphs from many bearing studies. Everyone knows that higher HTHS viscosity protects better than lower HTSH. Therefore, I'd say the BMW bearing issue was more along the lines of bearing design and engine abuse more than the oil viscosity used.




Similar in SAE paper 922342...



https://www.sae.org/publications/technical-papers/content/922342/
Quote:
These results were used to design a Field Test of nine oils in 45 taxicabs in New York City. The test oils (SAE OW-20 to 20W-20) were formulated to measure the effects of viscosity, viscosity index improver, and detergent inhibitor package. Bearing wear tended to be either low and unremarkable or very high, particularly in the thrust bearings. Oil performance was best expressed as the frequency of excessive wear, rather than by quantitative wear measurement. There were many instances of very high wear in cabs operated with the lowest viscosity oils but none in cabs with higher viscosity oils. Non-Newtonian oils appeared to provide slightly more protection than Newtonian oils of the same HTHS viscosity, and a higher quality adpack also appeared to provide benefits. However, these factors were secondary to the viscosity of the oil. HTHS viscosity was a better predictor of bearing wear performance than oil film thickness.


Originally Posted By: Gokhan
I think there is no doubt that the bearing design was the main culprit here but I bet if they ran the TGMO 0W-20 they wouldn't see the bearing failures they saw with the 10W-60. So, definitely some credit goes to AEHaas here, who successfully ran 0W-20 in his Ferrari.


No, you are misguided on the former claim, HTHS IS the bearing protector...when you run to the left of the Stribeck curve, you need to start replacing film thickness with additives...you are no longer in the zero wear regime (what they call full fledged hydrodynamic lubrication in the engineering texts), you are in the controlled wear regime.

As to the latter, how much of the performance envelope did AEHAAS actually use ?

Here's some Honda stuff on the ways in which engines are operated in different markets...


Drive your Ferrarri in the lower left area like the Average US Corrolla driver, 0W20 is probably fine...extend it to Ferrarri operational range in terms of load and RPM (the right hand side of the chart, and do it for an hour, and it would have been toast.

Originally Posted By: Gokhan
Alternatively, we can also claim that any engine that sees bearing failures with 0W-20 has also poor bearing design. Therefore, design the engine so that it could easily tolerate any oil from 0W-16 to 25W-60.


NO, simply NO...you design your bearings for the operational regime that you want them to operate in.

You have poo-poohed my claims derived directly from Honda papers that they are changing bearing design parameters, but here you are claiming that any bearing that fails on 0W20 needs a redesign...to operate on 0w20...

The push for fuel economy (and CO2) is creating the trend for thinner oils...and designers are responding.

 

[Gokhan]

Originally Posted By: PimTac
As Shannow posted, it’s no wonder some of the replies don’t add up. I’ve seen this a couple of times now and just attributed it to my old age and lacking in memory. The poster has to unclick the box so it’s a intentional act.

Ha! You were being gaslighted all the time after all!

 

[Shannow]

Originally Posted By: OVERKILL
Originally Posted By: PimTac
As Shannow posted, it’s no wonder some of the replies don’t add up. I’ve seen this a couple of times now and just attributed it to my old age and lacking in memory. The poster has to unclick the box so it’s a intentional act.


I do it sometimes when I've made a spelling or grammatical error, which I think is the primary purpose for its existence.


As do I...
to change content, or sometimes the entire direction of an argument, it's poor form. You should leave a reason.

 

[ZeeOSix]

Originally Posted By: Gokhan
We really have no idea about the bearing design, engine design, and oil quality/viscosity index in that plot, apparently from the late 1970's. I can't imagine you would see anything resembling that in a modern engine on a modern oil.

TGMO 0W-20 SN (2015 formulation): 35 cSt @ 40 C, VI = 226, HTHSV = 2.6 CP
M1 0W-40 SN (original formulation): 75 cSt @ 40 C, VI = 185, HTHSV = 3.8 CP
Castrol TWS 10W-60 SN: 160 cSt @ 40 C, VI = 173, HTHSV = 5.2 CP


I'm assuming you're talking about the plot I posted of HTHS vs bearing wear with different viscosity oils. Tested in the same bearing design - therefore, it's still valid data showing the effect of HTHS on relative bearing wear between the different viscosities.

Read what I originally said, that higher HTHS has always been shown to result in less bearing wear - every plot I've ever found looks similar to this one, regardless of how old the data is. This correlation has been known for a very long time. Also, generally speaking, higher viscosity oil will have a higher HTHS. Even your list shows that.

So I'd like to see some examples where: 1) Lower viscosity oil has higher HTHS than a thicker oil of the same basic formulation, and 2) Test data that shows that oil with lower HTHS results in the same or less bearing wear than a thicker oil of the same basic formulation.

 

[PimTac]

Originally Posted By: Shannow
Originally Posted By: OVERKILL
Originally Posted By: PimTac
As Shannow posted, it’s no wonder some of the replies don’t add up. I’ve seen this a couple of times now and just attributed it to my old age and lacking in memory. The poster has to unclick the box so it’s a intentional act.


I do it sometimes when I've made a spelling or grammatical error, which I think is the primary purpose for its existence.


As do I...
to change content, or sometimes the entire direction of an argument, it's poor form. You should leave a reason.




I do as well. Most of the time it’s to correct the spellchecker. Other times to add something I’ve forgotten. The post will show it has been edited though I usually do not leave a explanation.


“....Ha! You were being gaslighted all the time after all!....”

I have no idea what this means.

 

[Gokhan]

Originally Posted By: Shannow
opened up to 1.2 thou per inch

I had no idea what "thou" meant and I had to look it up. It's not used in US English.

It makes sense that it's expressed as a dimensionless parameter like the eccentricity.

However, I don't expect a linear scaling at the end of the day with all the parameters out there, including surface roughness, particle size, etc.

 

[Gokhan]

Originally Posted By: PimTac
“....Ha! You were being gaslighted all the time after all!....”

I have no idea what this means.

Ah, the phrase arises from the famous classic 1944 Ingrid Bergman movie Gaslight (based on a play written earlier), for which she won the best-actress Oscar. You should see it. It's a very good movie.

 

[PimTac]

Originally Posted By: Gokhan
Originally Posted By: PimTac
“....Ha! You were being gaslighted all the time after all!....”

I have no idea what this means.

Ah, the phrase arises from the famous classic 1944 Ingrid Bergman movie Gaslight (based on a play written earlier), for which she won the best-actress Oscar. You should see it. It's a very good movie.




I’ll check it out.


For whatever reason, this thread reminded me of a story from my Dad who spoke of some unscrupulous used car dealers way back when that added sawdust to the oil to make the engine quiet. A poor man’s moly in that respect. This was in the 40’s as I recall.

 

[Shannow]

Originally Posted By: Gokhan
Originally Posted By: Shannow
opened up to 1.2 thou per inch

I had no idea what "thou" meant and I had to look it up. It's not used in US English.

It makes sense that it's expressed as a dimensionless parameter like the eccentricity.

However, I don't expect a linear scaling at the end of the day with all the parameters out there, including surface roughness, particle size, etc.


OK, again what I said...it's the ratio that we START at...then move from there.
Originally Posted By: Shannow
Should have continues after the "start"...that's where we "start" in bearing design, a ratio of1 thou per inch, we don't start radial clearance.

The clearance, per the somerfed numbers on the bearing design charts is a ratio, not a linear dimension.

Then from that point you go through an iterative process of stability, temperature rise, side leakage etc.


I've never designed for particle size, and have never seen that designed into bearings...we filter the lubricant to remove particles.

But I'll humour you for a little.

IF you designed a bearing to clear a particle of a certain size, i.e. have it pass through the area of MOFT without scoring or scratching, you would have to specify firstly the acceptable MOFT...then go to the design curves...



And when you do that you pick a STARTing set of dimensions, which is typically 0.001" per inch of diameter, or in metric, 1 micron per mm...that's the advantage of deminesionless numbers, they translate into other measuring systems.

Then you go through the various phases of the design...side leakage and power loss determines the heat rise, which is then fine tuned with clearance, supply pressure etc. until you reach the operating point.

But, and I'll reiterate, I've NEVER designed for particle swallowing. You could never attain the MOFT within the bounds of reason to swallow anything significant...tell me what size particle these people designed their big end to swallow.


Some more on your misunderstanding of HTHS when it comes to bearings...

 

[Shannow]

Originally Posted By: PimTac
I’ll check it out.


https://www.businessinsider.com.au/what-is-gaslighting-2017-7?r=UK&IR=T

 

[Gokhan]

Yes, of course, I know that MOFT ~ HTHSV. You can go back to my posts six years ago when I said that. The question is how much MOFT is enough and how much MOFT is a waste in terms of fuel economy. Also, catastrophic bearing failure usually seems to result from other design variables. I remember one old paper (I think it was by SAE) where they couldn't fail the bearings on SAE 10W oil no matter what they did.

For what it's worth, here are some specifications for the 4A-LC engine (1985 Corolla) from the OEM repair manual (oil specified is SF or SF/CC 10W-30 through 20W-50):

 

[Shannow]

Originally Posted By: Gokhan
Yes, of course, I know that MOFT ~ HTHSV. You can go back to my posts six years ago when I said that. The question is how much MOFT is enough and how much MOFT is a waste in terms of fuel economy.


The question that I was answering was with regard to your posit about designing to swallow particles...wehich we don't, and I demonstrated.

The HTHS was per your red text in a previous post, expanding on my previous answer.

Note in your pics that the "limit" is 80 microns, just like the Clevite manual...

Originally Posted By: Shannow
https://www.mahle-aftermarket.com/media/...gs/eb-20-18.pdf

0.007 (17 microns) to 0.032 (80 microns) for the 4A-LC seems to vary wildly from the claimed standard.

 

[BrocLuno]

Originally Posted By: ZeeOSix

I've seen guys at the drag strip on a cold night sit in the staging lanes for over an hour with the motor off, and the oil will cool down substantially. Then they fire it up, do a short burn-out and hammer it at red-line down the strip. I'd bet the oil temperature isn't even close to full operating temperature. So what's going on in all the bearings during these episodes? ... maybe something not so good, like seen in these BMWs.

Did BMW have any other bearing failure fiascos on engines that ran oil thinner than the 10W-60?



Except they don't puke bearings. They may toss a rod, but that is usually a function of rod bolt stretch on the exhaust stroke (trying to stop and reverse a piston's inertia at 7K+ in a crank arrangement never designed to go that high ...). The bearings can usually handle the thicker cooler oil because 1.) they heat the oil internally due to surface speed, and 2.) the bearings in all drag motors I have ever worked on are 0.003 to 0.004 with with chamfered edges so they bleed oil quite well and to not block side leakage.

 

[Gokhan]

After skipping through 52 pages of various UOA's, I think there is no doubt that switching from 10W-60 to a thinner oil (mostly M1 0W-40) eliminated or at least alleviated the BMW M3 S65 engine connecting-rod bearing-wear problems for most owners. I think some reported even less wear or no wear with 5W-30.

BMW M3 S65 engine 10W-60 vs. 0W-40 UOA's (link)

My conclusion is that 10W-60 was indeed too thick for the design bearing clearances of this engine.

My general conclusion is that you can't go arbitrarily high in oil viscosity to reduce engine wear, which was clearly shown with UOA's in this engine. Just like xW-20 could result in bearing failures in some engines, xW-50 or xW-60 could also result in bearing failures in some others. Unfortunately, the simplistic minimum oil-film thickness (MOFT) argument that doesn't consider other design and lubrication parameters is often used to claim that thicker is always better for less engine wear.

 

[OVERKILL]

Originally Posted By: Gokhan
After skipping through 52 pages of various UOA's, I think there is no doubt that switching from 10W-60 to a thinner oil (mostly M1 0W-40) eliminated or at least alleviated the BMW M3 S65 engine connecting-rod bearing-wear problems for most owners. I think some reported even less wear or no wear with 5W-30.

BMW M3 S65 engine 10W-60 vs. 0W-40 UOA's (link)

My conclusion is that 10W-60 was indeed too thick for the design bearing clearances of this engine.

My general conclusion is that you can't go arbitrarily high in oil viscosity to reduce engine wear, which was clearly shown with UOA's in this engine. Just like xW-20 could result in bearing failures in some engines, xW-50 or xW-60 could also result in bearing failures in some others. Unfortunately, the simplistic minimum oil-film thickness (MOFT) argument that doesn't consider other design and lubrication parameters is often used to claim that thicker is always better for less engine wear.


Which perpetuates the fallacy that one can glean wear directly via UOA's and contrast the results from completely different formulated oils to determine "better" performance. You can't, you need tear-downs, this is all just WAG without tear-downs and measurements; junk science.

Rod bearings on the S54, and many will say on the S62, are considered a wear item, regardless of what oil you run. You aren't going to get 200,000 miles out of them using the engine as intended even if you had PFM in the pan. BMW's attempt to mitigate the issue of early failure, as I already noted, was to spec the TWS 10w-60. It's a bandaid, as no oil is going to "fix" the issue, which seems to have been a design issue. The issue with the S62 is a bit different, as its oiling system may in fact be the problem, not the engine, but that's a separate discussion.

 

[ZeeOSix]

Originally Posted By: BrocLuno
Originally Posted By: ZeeOSix

I've seen guys at the drag strip on a cold night sit in the staging lanes for over an hour with the motor off, and the oil will cool down substantially. Then they fire it up, do a short burn-out and hammer it at red-line down the strip. I'd bet the oil temperature isn't even close to full operating temperature. So what's going on in all the bearings during these episodes? ... maybe something not so good, like seen in these BMWs.

Did BMW have any other bearing failure fiascos on engines that ran oil thinner than the 10W-60.


Except they don't puke bearings. They may toss a rod, but that is usually a function of rod bolt stretch on the exhaust stroke (trying to stop and reverse a piston's inertia at 7K+ in a crank arrangement never designed to go that high ...). The bearings can usually handle the thicker cooler oil because 1.) they heat the oil internally due to surface speed, and 2.) the bearings in all drag motors I have ever worked on are 0.003 to 0.004 with with chamfered edges so they bleed oil quite well and to not block side leakage.


I was talking about guys who bring their everyday street cars that have the factory stock bottom end - not a specially built race motor. Guys doing what I described could be doing damage redlining with pretty cold oil and slowly wearing bearings out like in the troubled BMWs if the bearing design isn't ideal. Looked like the BMWs took many thousands of miles to achieve significant bearing wear.

 

[ZeeOSix]

Originally Posted By: Gokhan
For what it's worth, here are some specifications for the 4A-LC engine (1985 Corolla) from the OEM repair manual (oil specified is SF or SF/CC 10W-30 through 20W-50):

See Gokhan"s post for manual photos and bearing specs.


So the shop manual says the STD oil clearance range is:

Crank bearings: 0.0015~0.0029 inch.

Rod big end bearings: 0.0008~0.0020 inch.

And Toyota is specifying use of oil as thick as 20W-50 in a rod bearing that could be as tight as 0.0008 inch and still be within factory spec.

Obviosly, Toyota didn't think that thicker oil in tight bearings will smoke bearings if they are designed right (correct end clearance, etc), and also the oiling sytem is designed well to ensure ample oil supply.

Did this Toyota engine ever have any history of bearing issues if owners used 20W-50 it's whole life?