Engines that actually require Thick or Thin oil?

[Gokhan]

Originally Posted By: Shannow
"Standard" bearing clearances in design work start at 0.001" per inch of bearing diameter , making it a ratio, and therefore dimensionless.

There's no "standard 50 microns"

Well, I have 50 microns in my Corolla and the same goes for the newer engines. It has smaller bearings.

 

[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.

 

[Shannow]

Originally Posted By: Gokhan
Originally Posted By: Shannow
"Standard" bearing clearances in design work start at 0.001" per inch of bearing diameter , making it a ratio, and therefore dimensionless.

There's no "standard 50 microns"

Well, I have 50 microns in my Corolla and the same goes for the newer engines. It has smaller bearings.


link for clearances ?

and that's the "standard" for the M3 ???

 

[Gokhan]

Originally Posted By: Shannow
link for clearances ?

The link is my OEM repair manual. I could post the pic later.

4A-LC engine (1985 Corolla)

Connecting-rod bearing:

Standard clearance: 20 - 51 microns
Clearance limit: 80 microns
Standard diameter: 39.985 - 40.000 mm

Main bearing:

Standard clearance: 12 - 49 microns
Clearance limit: 80 microns
Standard diameter: 47.985 - 48.000 mm

 

[Shannow]

Originally Posted By: Gokhan
Originally Posted By: Shannow
link for clearances ?

The link is my OEM repair manual. I'll post the pic later.

4A-LC engine (1985 Corolla)

Connecting-rod bearing:

Standard: 20 - 51 microns
Limit: 80 microns
Diameter: 39.985 - 40.000 mm

Main bearing:

Standard: 12 - 49 microns
Limit: 80 microns
Diameter: 47.985 - 48.000 mm


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.


OK, so the "standard" clearance has basically half an order of magnitude.

And please explain how 50 microns is the "standard" for the M3, based on Corolla lack of correlation

 

[Gokhan]

What's more interesting here is the large acceptable range specified for the standard clearance as well as the wear/repair limit.

Oil that was specified at that time was 10W-30 through 20W-50.

 

[aquariuscsm]

This whole thing really does have me wondering,did Honda design the K24's bearings,etc,to thrive on a W20 oil?

 

[Shannow]

It was your statement as to what was "standard"...across manufacturers and realms. And you have demonstrated that your claimed "50 micron standard", in YOUR vehicle stretched from 20 to 80 in standard realm.

So the 10W30 to 20W50 "at the time"...did they tell you what oil to put in your engine as the tolerances stacked up...Oh Gokhan, your engine is particularly tight, so we suggest that you run the 10W30 up to 80,000 miles, and then switch to a 10W40 ?

Originally Posted By: Gokhan
tolerances and variations are the main culprit in bearing wear


I said that you didn't understand the differences, and your surprise demonstrates that I was correct.

 

[jstutz]

For me, I live in NC where the weather is relatively mild compared to most. The lowest temps i see may be 10F and the highest around 100F. For most engines in this climate, that are used in a standard fashion, you could run anything from 0w20 all the way to 5w50 and i doubt most engines would care much. I do believe that there are certain situations, that under severe conditions, that will matter. I have read of one situation that the cam chain tensioner uses oil pressure to create the tension from the chain to the tensioner pad. In certain situations where people have used thinner oils and track the car that the chain would rattle because there was not enough pressure created on the chain do the the very thin oil. I dont think this is overly detrimental to the engine but it is a situation you could avoid.

I dont know of any situations that under normal operating conditions that having a grade heavier or lighter would hurt anything. I think people would know that if you live in Alberta Canada, dont use a 20w50, in the winter, in your new 0w20 rated car.

 

[Gokhan]

Originally Posted By: Shannow
So the 10W30 to 20W50 "at the time"...did they tell you what oil to put in your engine as the tolerances stacked up...Oh Gokhan, your engine is particularly tight, so we suggest that you run the 10W30 up to 80,000 miles, and then switch to a 10W40 ?

You're beating the claims, statements, or conclusions that you said I made but I didn't. Interestingly, you've accused me of doing the same.

Regarding your definition of the standard (25 microns per 2.5 cm), my clearances don't fit in it either. Not only a lot smaller clearances are allowed but the connecting-rod bearing has a larger clearance despite the smaller diameter. Yet, the maximum standard clearance specified for both of my bearings is curiously right on 50 microns, which was my one if the reasons behind my 50-micron claim, along with the data on the newer Toyota engines, and this from the 1977 bearing-failure study (link):

"The crankshaft intended for operation in that particular block was then ground to give a diametrical clearance of 0.0020 to 0.0023 in (O.O51-O.O58 n~a) and a journal surface finish between II and 14 microinches [0.28-0.36~m (aa)]. A new crank and bearing set was used for each test. Bearing clearance was controlled since clearance affects not only the load capacity but also the oil flow rate through the bearing and thus the bearing temperature. Clearance was controlled on the high side of the production limits since high clearance reduced the bearing load capacity, and reduces sensitivity to changes in journal diameter."

Can we actually have a fruitful discussion instead of cherry picking and slamming?

 

[ZeeOSix]

Originally Posted By: Gokhan
BMW ///M3 data. All clearances are around the standard 50 microns (0.0020 in) or less. It specs 10W-60 but later they allowed 0W-40.

There is a lot of information and speculation into why the bearings were failing.

Now, let's have a panel that will go through the whole page and decide whether the culprit was the thin oil, thick oil, or something else.

BMW ///M3 bearing-failure analysis


I skimmed through that super long thread, and one thing that was mentioned was the thought that the bearing side clearances were way too tight, which might have hindered the natural hydrodynamic oil flow through the journal bearings, especially with thick cold oil and when running the engine in relatively high RPM ranges before the oil was at full operating temperature.

Even 5W-20 oil is many magnitudes thicker at 50 F than 10W-60 is at 200 F ... the point being, if a journal bearing isn't designed properly it will also probably destroy itself over time if the engine is fired up and revved high with cold oil - even 5W-20.

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?

 

[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.

 

[ZeeOSix]

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


Came across this post on that BMW thread: Apparently thinner oil and careful oil warm-ups didn't seem to cure the OEM bearing wear issue. Points to bad bearing design IMO.

Click on image to expand:

 

[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

The KV40 number of the 10W-60 is very worrisome to me, about five times that of TGMO.

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.

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.

Last but not least, oil temperatures can exceed 150 C and HTHSV alone doesn't indicate how thick an oil is at elevated temperatures such as 170 C, which is when bearing failures can really happen. On top of that, oils can shear. Therefore, the viscosity index (VI) and base-oil quality should always be considered. A GTL or PAO 0W-20 can actually be thicker at 170 C than a Group II or Group III 5W-30. SAE viscosity and HTHSV alone don't tell you how thick an oil is at the most perilous conditions.

 

[OVERKILL]

Originally Posted By: Gokhan
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.


That's a rather wild posit. You do realize that the engine originally spec'd an LL-01 5w-30 and was "upgraded" to the 10w-60 to aide in mitigating the bearing failures. So your bet literally runs 180 degrees from the direction BMW took on this. Regarding Haas, he never got the engines up to operating temperature and was quite forthcoming with the fact that he drove like a grandmother with the RLI 0w-20 in the sumps. NOT using the cars as intended was one of the primary reasons he was comfortable using a significantly thinner lubricant than spec'd.

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.


Ford's 5.0L Coyote engine is an excellent example here with the "regular" version spec'ing 5w-20 and the "Track Pack" version spec'ing 5w-50. Identical engines.

Originally Posted By: Gokhan
]Last but not least, oil temperatures can exceed 150 C and HTHSV alone doesn't indicate how thick an oil is at elevated temperatures such as 170 C, which is when bearing failures can really happen. On top of that, oils can shear.


Yeah, oils can shear, that's why HTHS is called High Temperature High Shear, it's literally in the definition of the designation. Are you implying that High Temp High Shear, which is measured at 150C, suddenly changes dramatically with a 20C increase in temperature that isn't aptly represented in the test designed to determine High Temp High Shear performance?

Originally Posted By: Gokhan
Therefore, the viscosity index (VI) and base-oil quality should always be considered. A GTL or PAO 0W-20 can actually be thicker at 170 C than a Group II or Group III 5W-30. SAE viscosity and HTHSV alone don't tell you how thick an oil is at the most perilous conditions


What's this based on? Have you run the HTHS test at an elevated temperature on a 0w-20 to confirm that a lower group oil with a 3.1cp HTHS drops at a different rate past the 150C test point than an oil with a 2.6cP HTHS?

This is drifting into wild speculation that defies the purpose of the tests defined for the purposes outlined. Without something to back it, this becomes ridiculous conjecture

 

[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.

 

[Shannow]

Originally Posted By: Gokhan
Regarding your definition of the standard (25 microns per 2.5 cm), my clearances don't fit in it either. Not only a lot smaller clearances are allowed but the connecting-rod bearing has a larger clearance despite the smaller diameter.


Originally Posted By: Shannow
"Standard" bearing clearances in design work start at 0.001" per inch of bearing diameter , making it a ratio, and therefore dimensionless.

There's no "standard 50 microns"


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 had one bearing (14" diameter, on a Parson's Erith) that needed to be taken out and opened up to 1.2 thou per inch to operate at acceptable temperatures.
Another (20" diameter, 20" long) that was operating unstably, which responded to a 10C change in oil supply temperature until a shutdown, then required an entire generator re-alignment, and a restriction in the oil supply line to cure.

I do bearings...bearings were a big part of my engineering career, I understand them, have designed them, and designed lubrication systems for them.

 

[Shannow]

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.


You can untick the box when you edit.

That's why so many replies look ludicrous, as there are often many edits while a person is replying to a post.

 

[PimTac]

Originally Posted By: Shannow
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.


You can untick the box when you edit.

That's why so many replies look ludicrous, as there are often many edits while a person is replying to a post.



I didn’t know that. I assumed the edit notification would show up with any change in the post.

That’s a weak link in the system.

 

[Shannow]

Originally Posted By: Gokhan
Last but not least, oil temperatures can exceed 150 C and HTHSV alone doesn't indicate how thick an oil is at elevated temperatures such as 170 C, which is when bearing failures can really happen. On top of that, oils can shear. Therefore, the viscosity index (VI) and base-oil quality should always be considered. A GTL or PAO 0W-20 can actually be thicker at 170 C than a Group II or Group III 5W-30. SAE viscosity and HTHSV alone don't tell you how thick an oil is at the most perilous conditions.


History lesson...HTHS was developed specifically for what happens in bearings...High Temperature High Shear.

It was found that the standard J300 grades for kinematic viscosity didn't offer the protection that the grading system would suggest, and research was done into what actually happens in engines (hint - High Temperature High Shear), so one set of researchers drilled into a main bearing of a test engine and tested the "apparent" viscosity that the bearing saw at elevated RPM...and came up with this...that polymeric viscosity index improvers reduce the "apparent" viscosity in bearings



This was the start of the push for HTHS in the J300 specs...to get oils to provide minimum HTHS in bearings, which OPERATE in HTHT regimes.

Note that 10W40 initially had an HTHS minimum of 2.9, and was probably the reason that M1 5W20 when it first came out offered the same "protection" being a VIIless (I've read the papers, there were no VIIs in the original M1), it was in all likelihood 2.9 also...

So...
HTHS IS the viscosity/temperature point that's chosen, by the industry for bearing protection.
I would dearly love you to show me a 0W20 with a higher High Shear viscosity at 170 than a 5W30...and show me the engine that was needing it.