Another "Taxi" Study: Relationship of Engine Bearing Wear and Oil Rheology 872128

[kschachn]

" It is still a truth that the only real benefit to thinner oils is slightly improved fuel economy."

...And maybe less wear with thinner oils in an appropriate application:
Older post:
Compared Enzo Ferrari UOA from years ago: This is my neighbor’s 2003 Ferrari Enzo with a total of 8,800 miles (?fully broken-in) on the left column and my 2003 Enzo with a total of 4,400 miles on the right column (middle 2 columns, earlier UOA of my car). Both cars had about 1,400 miles on the oil. His obviously had more break-in time. He had the oil changed by the Ferrari dealer using the required 10W60 Shell Helix Ultra Racing oil. I ran 0W30 Castrol GC in the second column, the original formula of 0W30 Renewable Lubricants Inc. in the 3rd column and the “new and improved “ RLI “Dr. Haas” Enzo formula in the last column.

Tested my Enzo oils by Terry Dyson. His testing counts larger particles as well as all the smaller ones so other labs may give false lower values. At no time has the oil temperature in this engine gotten above 180 F. What is particularly interesting is that the original RLI formulation dropped to a 20 grade, the newer formulation did not.



OILS: ….Shell……. GC…... RLI….... RLI - “Dr. Haas Enzo Formula”

Iron___________ 32...11...7...3 (Fe in RLI VOA =2)

Chromium ____
Nickel __________2...1....0...0

Aluminum _____11...3....2...0

lead ___________ 16...0....3...1

Copper ________25...8....4...3

Tin ___________
Silver ________
Titanium _____
Silicon _________ 7...3....4...2

Boron _________ 1...3...16..17

Sodium _______ 8...3....10...8

Potassium ____
Molybdenum _
Phosphorus ___1026...935…1032…698

Zinc __________ 1135...1228…1055...988

Calcium ______ 1454…167...2108…1898

Barium ______
Magnesium __1219...526…53...19

Antimony ____
Vanadium ____
Fuel %Vol ____
Flash_______not done..335..320..300

Abs Oxid _____ 34...10..127...95

Abs Nitr ______ 11....8....8....7

Wtr %vol ____
Vis CS 100C __ 15.8....11.8….8.6….9.8

Vic CS 40C___not done…66….44….48

SAE Grade _____40....30....20....30

Gly test ______NEG…..0.37 “not antifreeze”…...0…..0

TBN _________not done...7.9....5.9...6.4

TAN _________not done...1.7....1.4...1.3

Visc Index___not done…154...177...192

Soot_________not done...0....0.01....0

Note the resistance to viscosity drop in the newer 0W30 formulation despite more fuel dilution.

Ali

Still trying to use a $30 spectrographic analysis to show comparative wear? Even after the links and post by edhackett in this thread? And the many other posts about what a simple UOA shows and what it most certainly does not show?

And what about his testing that allows him to count larger particles as well as smaller ones? Please elaborate.

 

[ZeeOSix]

Here is an example of old science to new science. On this link in figure #8 there are two bearings set to zero eccentricity and .0004 eccentricity. Notice the .0004 eccentricity that the MOFT is tighter than the zero eccentricity. The MOFT is at maximum with that clearance, bearings are stable. Maximum MOFT is controlled by bearing clearance and the shape of the bearing.
https://www.kingbearings.com/wp-con...mization-of-clearance-engine-professional.pdf

It is all dynamic to RPM and loading, but in general the viscosity needs to be thinner in tight clearances.

Not sure what you mean by "bearings are stable". Crankshaft main bearings are "more stable" than rod bearings. Rod bearings usually wear and fail way more often than crank bearings. Rod bearings take a large beating with all the mass inertia on top of all the different loads on them. I'll have to dig up the graph of a rod MOFT as a function of crank angle - it's nowhere being close to stable. The rod bearing MOFT that King Bearing is showing is probably the smallest MOFT seen over a whole 720 deg of crank rotation (two rotations to cover all four piston strokes).

I see you removed your sentence after the PDF link.

... but in general the viscosity needs to be thinner in tight clearances.

If you're talking about tight bearing clearances, then that is not a true statement. Again, every King Bearing piece of journal bearing info always shows that thicker oil in bearings always gives more MOFT. And bearings are force fed oil by the PD oil pump, so that guarantees that bearings get oil, regardless of the oil viscosity. That's why PD oil pumps are used on engine oiling systems.

 

[fantastic]

Another thought on that is; 9 and 10 speed automatics that result in less rpm drop between gears and keep the engine in its sweet spot.
Clutch engagement on manual transmissions is a learned skill to avoid lugging.
They say that a manual transmission is an anti-theft device for millennials.

Plain bearings are said to "self-pump" to some extent as long as there's an oil supply. (FB University)
Prime the system and it's good to go theory begat variable oil pumps.

Obviously, that statement is not true. I'm a millennial & was born in 1984

Millennial's start in the early 80's.

 

[Bill_W]

Not sure what you mean by "bearings are stable". Crankshaft main bearings are "more stable" than rod bearings. Rod bearings usually wear and fail way more often than crank bearings. Rod bearings take a large beating with all the mass inertia on top of all the different loads on them. I'll have to dig up the graph of a rod MOFT as a function of crank angle - it's nowhere being close to stable. The rod bearing MOFT that King Bearing is showing is probably the smallest MOFT seen over a whole 360 deg of crank rotation.

I see you removed your sentance after the PDF link.

If you're talking about tight bearing clearances, then that is not a true statement. Again, every King Bearing piece of journal bearing info always shows that thicker oil in bearings always gives more MOFT. And bearings are force fed oil hy the PD oil pump, so that gaurentees that bearings get oil, regardless of the oil viscosity. That's why PD oil pumps are used on engine oiling systems.

The problem with rod bearings happen when the rod is stretched. I hate to circle this but since I am a dummy personally I have to rely on this link again. (sorry mods)
https://www.substech.com/dokuwiki/d...al_eccentricity_for_high_performance_bearings

Again the conclusions at the end is important.

 

[AEHaas]

"Re: Volatility - Higher Noack oils will "flash off" more in the very hot ring zone area. Running lower Noack oil will ensure better boundry lubrication and less deposits in the ring zone. This is why I look at Noack numbers when shopping for oil."

Another thing I also look for in an oil of my choosing.

 

[wpod]

He cares!

He does what he is supposed to do, a proper job.

 

[wpod]

When was the last time you rode in a cab in a big city? It's not uncommon for the experience to feel like everyone is racing from light to light.

That is not hard.

 

[demarpaint]

He does what he is supposed to do, a proper job.

Yes.

 

[kschachn]

Again the conclusions at the end is important.

And you are making many that are not correct.

 

[wpod]

I'll be a 2-day HPDE event at VIRinternational Raceway in a few weeks....I'll make sure to poll the group "What oil are you using?"

They will all be running 0W-5!

 

[Bill_W]

And you are making many that are not correct.

Thanks, I will file that in my wisdom files.

 

[ZeeOSix]

The problem with rod bearings happen when the rod is stretched.

Yeah, that's because rods have some wildly varying loads and forces on them. The rod bearings take more of a beating than the crank bearings.

Result of high loads and zero MOFT ...

 

[Fahrvergnügen]

And you have VW dealers using it in everything based on some experiences I've read about with dealer oil changes. There are likely quite a few VWs on the road meant for 502/504 that have 508 at this minute.

As a former VW tech, can tell you parts only ordered 504/507 and 508/509 oil. All the old 502/505.00 or 505.01 speced engines got 504/507. And actually in the GTI that called for 508 got 504/507 0w30 from Mobil. I’m currently at BMW and we don’t put 0w20 in anything as parts doesn’t even carry it, It’s all 0w30 Longlife-01FE. Just an FYI

 

[Jetronic]

Would you?

I wouldn't run it as I have no idea how viscous that non-existing grade is.

 

[ZeeOSix]

I wouldn't run it as I have no idea how viscous that non-existing grade is.

If the manufacturer is calling it a "0W-5", then it's most likely less viscous (has a lower KV100) than a 0W-8.

 

[ZeeOSix]

And for those who are using the thicker oils in your specific vehicles: How do you know that those particular oils are in fact giving you better results than a thinner oil might give you. Are you tearing down your engines periodically to show wear levels? Are you comparing the wear to thinner oils within the same engines? I believe you are just making assumptions.

Only a multi-million dollar and very controlled study could find the answers to that - like what some oil manufactures do. But based on the science of Tribology and the various controlled studies done in labs and some in real world use conditions, the overall data still points to the fact that thicker oils provide more film thickness and therefore more wear protection. When you throw in all the factors involved like specific oil AF/AW additive formulations, specific engine designs, especially the oiling system and engine component materials, etc, it can get skewed. But when all other factors are held constant (including oil formulation) beside viscosity, it always shows per the basic laws of Tribology that higher viscosity gives more film thickness between moving parts. Wear protection is mitigated by film thickness first, and film strength second.

Maybe you should try thinner oils and experiment?

Nah, no thanks ... we are all watching your experiments.

 

[ZeeOSix]

Results concluded by the author: Statistically significant that 20 grade oils can be safely used in cars and light trucks.

"Safely used" is a pretty open ended statement. All these discussions are about wear rates, not engines blowing-up or failing somehow ... but about wearing more with thinner oil compared to thicker oil. All engine wear studies pretty much conclude that engine wear increases as the oil becomes thinner and thinner, unless specific engine design features are used, like what's being done in engines that specify 0W-16 and below. API says do not use any 0W-16 or below in any vehicle specifying a xW-20 or higher. There's a reason for that, as is discussed on a daily basis on BITOG.

Wonder what the "statically significant" test results would be if they were all running 0W-5 when they were all recommending to use xW-20 or higher? I don't think a sample of one will be enough data ... or maybe it will be.

 

[ZeeOSix]

Always said: oils for the application, not to be afraid of thinner oils when appropriate. More HP, better fuel economy, better for the environment.

But if you used all the HP (like in a track event), then you'd need thicker oil for better engine protection. It's a vicious circle, lol. Even with a big SUV with the aerodynamics of a brick, it really doesn't take much HP to cruise down the highway at 70 MPH ... like around 35-40 HP at most.

 

[ZeeOSix]

No but I wouldn't be afraid to run the oil the OEM calls for in my vehicle either if that were to be a thinner oil like 20W and below like many BITOGers if my use case was "just driving around".

If an engine manufacture specs an oil thinner than xW-20, then the engine most likely has some unique design features to run oil that thin. Again, it's also why API has a unique spec and logo for oils below xW-20.

 

[Jetronic]

If the manufacturer is calling it a "0W-5", then it's most likely less viscous (has a lower KV100) than a 0W-8.

assumptions...

Didn't Neo have a 0W-5 when the lowest grades were xW-20? I recall it wan't much thinner, if any, than a 20.