All You Guys That Think OEM Recommended 16 or 20 Weight...

I'm liking the more technical side of this thread.

When it comes to minimum oil film thickness and how it relates to OEM, do the engineers that spec the lowest grade in the manual (0W-20, 0W-16, or whatever) assume the worst case scenario of say high gear, 1500 rpm, WOT, and say a 6% grade uphill for 3 miles?


I imagine cruising down the interstate at 65 mph and 1500 rpm is low load and not a big deal.
 
JSTOR has the entire Dingens, you know them already: www.jstor.org/stable/44471538

But we're not interested in oil qualities here, we're interested in steering you towards true engine operation. Steer you away from your Sommerfeld Blues wherein you want to deal with the variables as much as you want to steer me towards your newer PD pumper studies, could that be?

HTHS is generally relevant at idle, not so much at five, ten, twenty millions per second instead of the one million in HTHS. That's shear thinning and that's why you had to be pointed towards ultra shear... Those people and others weren't judging oils or grades, they were interested in the skills and tools of their time – ultimately the HTHS as such.
If a guy and his Honda used some LM 5W-50 and killed an egine or two, that's not much of a brand aspect here either, although the LM might have used one of the thinnest base oil blends. It's merely one more situation you troops can't deal with in any reasonable way, cause all your tools in any case are the hammer.

No, regarding oils, it's a fundamental feature, that a non-intelligent 5W-50 viscosity molecule gets properly slowly PD pump-motivated and warmed up en route, then after entrainment experiences more viscous heating while the VII components align and bow to the load under ultra shear – just in time for getting together as thin as possible when the load is maximized. What's the shear rate over a 50mm bearing roughly? Three times 50 x 150, divided by 1000 for meters, divided by OFT. Walks towards 20 millions per second. Not that much room for speculation. The thickness ain't there. The temperatures for VII-action would be there, but...

Almost every engine of course will have sufficient BOV from a 5W-50 under almost all conditons, but that's not really because of very advanced 5W-50 oils among others. It's simply because the actual viscosities in the bearings are usually sufficient anyway – as they'd be with an OSP SAE not-even-20 (or the 20W-20 from page 8, as long as temps are kept under control). The #50 is a primitive cure for temps not under control. Normally not ever a requirement as such.

Then the alternative remains Ready4War's: Not necessarily so much focus on boosted VI, more direct rejection of too high viscosities as such. The guys also mentioned this to a degree.
GM's default monograde for the engine design work for ages was the 6cP? Why not, probably.

Either way the deficits are classic BITOG and hardly ever anyone else's.
 
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But we're not interested in oil qualities here, we're interested in steering you towards true engine operation. Steer you away from your Sommerfeld Blues wherein you want to deal with the variables as much as you want to steer me towards your newer PD pumper studies, could that be?
But the oil quality/formulation does play a role in how the HTHS viscosity behaves. And that also ties into the Sommerfeld number (S), which then determines the instantaneous operating MOFT. The bearing physical design (l/d ratio), RPM and loads of course also play a role.

Go read from equation (3) on page 49, and look at Figure 4 on page 50 in the link below. Figure 4 says the MOFT is always increasing with a larger Sommerfeld number, and even says that the multi-grade oil gave better MOFT at higher S numbers. My whole argument is that the MOFT will increase with increased oil viscosity (meaning a higher HTHS at whatever shear rate) with higher RPM if all other factors are held constant. You are only finding information where certain oil formulations have weak HTHS viscosity which hurts the building of MOFT at high RPM in a journal bearing.

The point is, the Sommerfeld relationship is valid, and the real question is how does a specific oil formulation behave in a specific engine. The guys doing those tests might not have even been able to accurately measure HTHS viscosity above 1M/s^2 shear rate in the lab and therefore had a hard time getting a good Sommerfeld correlation. With all other variables that effect MOFT held constant, an oil with higher HTHS viscosity (the viscosity inside the bearing at whatever actual shear rate) is going to result in higher MOFT than an oil with less HTHS viscosity at that same shear rate. Do you actually believe Sommerfeld's work? It's not a stretch to see that if the oil HTHS viscosity suffers inside the bearing due to whatever factors, then the MOFT will also suffer. I doubt you are going to find any study that says with all Sommerfeld factors held constant except the actual viscosity inside the bearing, that higher viscosity inside the bearing is going to reduce the MOFT.


HTHS is generally relevant at idle, not so much at five, ten, twenty millions per second instead of the one million in HTHS. That's shear thinning and that's why you had to be pointed towards ultra shear... Those people and others weren't judging oils or grades, they were interested in the skills and tools of their time – ultimately the HTHS as such.
If a guy and his Honda used some LM 5W-50 and killed an egine or two, that's not much of a brand aspect here either, although the LM might have used one of the thinnest base oil blends. It's merely one more situation you troops can't deal with in any reasonable way, cause all your tools in any case are the hammer.
Whatever the viscosity inside the bearing is at operating conditions is still relevant. Yes, maybe the xW-50 oil they used didn't do well in those engines at high RPM and high temperatures due to HTHS inside the bearings falling way to low under those conditions. How do you explain motorcycles revving at 10,000+ RPM for long periods of time running xW-50 oils? Better oils? ... maybe those S2000 guys should be running motorcycle oil in their engines. It could have been that the specific oil they were using just wasn't up to the task, regardless of the viscosity. A lower viscosity oil of the same exact formulation would be just as bad or probably even worse under the same engine conditions.

No, regarding oils, it's a fundamental feature, that a non-intelligent 5W-50 viscosity molecule gets properly slowly PD pump-motivated and warmed up en route, then after entrainment experiences more viscous heating while the VII components align and bow to the load under ultra shear – just in time for getting together as thin as possible when the load is maximized. What's the shear rate over a 50mm bearing roughly? Three times 50 x 150, divided by 1000 for meters, divided by OFT. Walks towards 20 millions per second. Not that much room for speculation. The thickness ain't there. The temperatures for VII-action would be there, but...

Almost every engine of course will have sufficient BOV from a 5W-50 under almost all conditons, but that's not really because of very advanced 5W-50 oils among others. It's simply because the actual viscosities in the bearings are usually sufficient anyway – as they'd be with an OSP SAE not-even-20 (or the 20W-20 from page 8, as long as temps are kept under control). The #50 is a primitive cure for temps not under control. Normally not ever a requirement as such.
That's why I asked if these S2000 guys who smoked the engine had any oil pressure and/or oil temperature data. Any oil cooler being used? If they had any engine data logging that could have maybe lead to some other factors involved. There are all kinds of factors that could be involved:

Was the oil crap to start with - bad formulation?
Were these cars modified in any way (turbos, tunes, etc)?
Was there any pre-ignition/knock events going on, which can cause big rod loads?
Were these engines rebuilt, and if so what were all the bearing clearances - maybe some setup too tight?
What condition were the bearings in before the top speed runs - previous damage?
Was the oil really a 50 to start with when new?
Was the oil level low?
What did the oil level go to during the top speed near redline use?
Was the oil sheared down a lot already from previous hard use and many miles?
Was the oil fuel diluted?
Was the oil filter new or did it have lots of miles and debris in it?
Was the oil filter free flowing enough at prolong high RPM?
Did the oil filter go into bypass and send a bunch of debris into the oiling system?
Was the oil filter cut open to ensure there was no media tearing, which could have sent some downstream?

As far as the PD pump (your favorite subject, lol), if in good shape, it would pump the same volume of hot oil if not in pressure relief. I highly doubt it was in relief with hot oil, regardless of viscosity. Was the pump modified in any way? Was the pressure relief working correctly? What is the pump pressure relief set to, and what was the max oil pressure seen during the top speed run?
 
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I'm liking the more technical side of this thread.

When it comes to minimum oil film thickness and how it relates to OEM, do the engineers that spec the lowest grade in the manual (0W-20, 0W-16, or whatever) assume the worst case scenario of say high gear, 1500 rpm, WOT, and say a 6% grade uphill for 3 miles?


I imagine cruising down the interstate at 65 mph and 1500 rpm is low load and not a big deal.


So I was pushing it running 0w20 over mountain passes at mid 90’s temps for well over 3 miles?
 
Same with this King now: Where's the graphing coming from, what was done?
Do you think they know anything about engine journal bearings?



 
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I stopped even reading about your beliefs and traditionals and misheard lyrics and stuff. Haven't noticed how I started asking you? Asking you to tell what had been done by your guys. I could find the King company if I were interested but asked for your newer studies or info about the pics you used.

Okay, what would you guess, Shell was imagining there, if not one aspect, influence, new world to discover to then feed into equations?:
(I'm not shown your page 49 I guess, but that's okay ;-)


shearthinning.jpg




Imagine ignoring shear thinning? No, they are putting it to good use. In addition of course nowadays advanced base oils with better VI plus/or advanced VII strategies are put to good use to get other viscosities down simultaneously (between 100°C and 120°C, between 80°C and 100°C, above 40°C and below 40°C and at 40°C). Thereby also helping cleanliness, as such VII blends can improve ring area depositing for example.
This fourth red square alone easily tells you where they're seeing oils operated. And that the classic BITOG-imagined thickness as load bearing isn't even there.
Okay, lugging around below idle rpms it would be there, but then the temperatures are less critical when lugging around below idle rpms – and above all an oil for this direction in an engine meant to do this tends to be a monograde or a 1500rpm-20W-20 from page 8 here. Somewhat appropriately cooled, maybe.






Well, useless to fall for ever perpetuated activist disinterest and worse. Keep posting freshest findings from newest studies at some distant point in time, or the hollow jamboree for others, it's fine here.
A thinking person is long nudged into emancipation by now, easy entries were offered, half a dozen links to engine experimenting and stuff depicted. Some people are still phantasizing past your sommerfeld Blues, but it's up to you to inform them about proper upright curve forming and pages with equations to avoid such in the brighter future of whatever. Address it all, address them all!

rodmoftg.jpg

China dreams 2019 or so



Sincerely awaiting
 
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The "worst case scenario" simply does not occur for me.

Most of my driving is on flat surfaces with light "payloads."

SFO<>OAK<>SJC
Less than 150#

Sometimes jobs take me over the Altamont Pass (not much of a grade) to the huge Fullfilment Centers/Logistic Warehouses in Tracy & Patterson.
The RPMs are consistently in the sweet spot of 1500 to 2800.
D-4S.
eCVT.
Electronic Oil Pump, Water Pump/Thermostat.
Sophisticated computer controls.
For The Win.
 
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I stopped even reading about your beliefs and traditionals and misheard lyrics and stuff. Haven't noticed how I started asking you? Asking you to tell what had been done by your guys. I could find the King company if I were interested but asked for your newer studies or info about the pics you used.

Okay, what would you guess, Shell was imagining there, if not one aspect, influence, new world to discover to then feed into equations?:
(I'm not shown your page 49 I guess, but that's okay ;-)

View attachment 68356

Imagine ignoring shear thinning? No, they are putting it to good use. In addition of course nowadays advanced base oils with better VI plus/or advanced VII strategies are put to good use to get other viscosities down simultaneously (between 100°C and 120°C, between 80°C and 100°C, above 40°C and below 40°C and at 40°C). Thereby also helping cleanliness, as such VII blends can improve ring area depositing for example.
This fourth red square alone easily tells you where they're seeing oils operated. And that the classic BITOG-imagined thickness as load bearing isn't even there.

I'm aware of HTHS viscosity, and that at shear rated above 1^6/sec that the viscosity could nose-dive like the graph above (which is just an extreme example of two oils that may not really exist). Every oil would have its own specific curve if the shear rate was extended out to 1^9/sec. Used oil that has already sheared or become fuel diluted makes it worse.

Following is from:

1629936300288.png

1629936316471.png


HTHS values in oil manufacture specs are at 150C and 1^6/sec - as we all know. Assuming the S2000 has a 2-inch diameter big rod end journal and runs at assumed MOFT of 20u, then at 8800 RPM the shear rate in the MOFT layer would be around 46^6/sec ... not even in the 1^7/sec region yet. If the MOFT layer was at 10u then the shear rate would jump up to 92^6/sec. Of course, if the oil temperature inside the bearing is getting way hotter than 150C then the HTHS viscosity goes down even more and the MOFT also goes down as a result and the shear rated goes up because the oil film is smaller. It's like a dog chasing it's tail. Or if the oil was already sheared because of a fare amount of miles on the oil (which most xW-50 do), and possibly fuel diluted on top of that due to an overly rich modified tune, then at 8800 RPM for long periods of time it might not do very well. All kinds of possible factors like in post #224. Maybe those S2000 guy show blew-up the engine got a UOA to give any clues.

BTW - Looks like Honda changed the max PRM specs for newer S2000 engines.
1629932990160.png


The Sommerfeld term that includes viscosity, RPM and load that determines the MOFT can obviously be influenced by all three factors, and if the oil viscosity at shear rates above 1^6/sec fall off a cliff then I agree that can certainly effect MOFT at higher RPM. Likewise, at higher RPM the inertial forces from the rod and piston assembly can put increased load (in addition the combustion load) into the bearings ... and the load pressure term (P) will be more sensitive to the load based on the physical l/d of the bearing. Bearings with a very narrow width will be more sensitive to combustion and RPM inertial load.

Anyway the main point I was trying to get across in all this discussion was that if all factors except the oil viscosity remained constant, that a thinner oil of the same basic formulation (and viscosity loss at shear rates over 1^6/sec) would still give less MOFT compared to thicker oil used in the same exact engine conditions. Even if the MOFT did decrease with RPM due to the factors discussed above, it would decrease less with thicker oil vs a thinner oil of the same formulation.

Per Sommerfeld, if only the viscosity increased, then the MOFT will have to also increase with all other factors remaining constant. Some of the real world testing does indicate that there are pretty good correlations between test data and the Sommerfeld number - if the Sommerfeld number increases, so does the MOFT. This subject matter is more complicated than it first appears, and there are all kinds of studies that agree, and some that don't agree. And who knows just how accurate some of the real world measurement methods are to try and correlate those measurements to the Sommerfeld equations. So far over the last 100+ years, Sommerfeld hasn't been show down in flames.

On a side note - if using thicker oil actually caused the MOFT to decrease vs a thinner oil at high temps and high RPM then manufactures of high performance cars wouldn't say to use a thicker oil for sever conditions or track use. And motorcycles that rev to the moon and typically run hotter oil temperatures wouldn't be specified to use xW-40 and xW-50 oils.

Following is from:

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1629934732131.png

1629934839795.png


Anyway ... these kind technical discussions are always good overall IMO as it makes some people do more research about the subject matter and hopefully broaden their viewpoints. Over and out. :)
 
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