Toyota TGMO 0W-20 SN VOA with VI, TBN, and TAN

[CATERHAM]

Originally Posted By: dailydriver
Originally Posted By: CATERHAM
Originally Posted By: dailydriver

How do the MRVs compare between these two oils and also M1's AFE/EP 0W-20, for extreme cold weather use??

My friend your memory is slipping.
You got all the spec's for Sustina 0W-20 a while ago and it's MRV is pretty much on par with M1 AFE/EP 0W-20 at 9,630cP..
We don't know what it is for the other OEM 0W-20s but for the original Nippon Oil made version of TGMO it's MRV was 18,000cP.
The intention of the OEM 0W-20s like TGMO is to be as light as possible at more typical start-up temp's, not extreme cold.


So, for someone in a VERY cold climate, for a WINTER OCI, you would suggest either the Sustina, or the M1 EP/AFE over the TGMO??

Just how cold does the ambient temp have to be for the TGMO to have a flow/pumping problem as compared to the M1 and Sustina products??

(I guess I cannot grasp the concept of MRVs vs. V.I.

)

Yes if you are routinely starting an engine unaided at Temp's that will hit -40 degrees then either M1 or Sustina would be your best choice.
But if you're never seeing near that cold it's VI that matters most and for 0W oils viscosity graphs are probably good down to -20C or even -25C. And if one still wants to use TGMO at super cold Temp's it will still work very well especially compared to a heavier grade like M1 0W-40.

 

[Gokhan]

Originally Posted By: CATERHAM
Based on my first hand experience, TGMO is lighter at operating Temp's than every 0W/5W-20 I've used and that includes a 5W-20 Dino. The only oil that is lighter is Sustina; i haven't tried the Idemitsu made MGMO.

You're talking about a 1 - 2 psi difference on your oil gauge? How do you know it's not due to another effect, such as a different type of oil filter, more dirt in the filter, even an unusual batch of oil, etc.?

 

[CATERHAM]

We're talking a very significant 6-8 psi difference at 85C IIRC and it's the huge difference in their VIs that reason.
Obviously at higher oil temp's the operational viscosity difference will decline as both oils have the same nominal HTHSVs.

 

[Shannow]

CATERHAM, do you still stand by your statement that TGMO starts out of specified grade ?

 

[Gokhan]

Of course, TGMO 0W-20 SN will have less kinematic viscosity at 80 C because of its ultra-high viscosity index. I was talking about the standard, 100 C kinematic viscosity.

That 6 - 8 psi difference you saw is merely representing the kinematic-viscosity difference of the oils at 80 C going through your oil pump.

 

[CATERHAM]

No I said 85C and OP correlates with HTHSV not KV.
83C-93C is the normal operating oil temp's for most engines.
A lower OP reading at the same OT and engine rpm represents a lower operational viscosity.

 

[Shannow]

Originally Posted By: CATERHAM
83C-93C is the normal operating oil temp's for most engines.


Guess where this is where we ask where that "fact" comes from...plus evidence that TGMO is lower than 2.6 HTHS, placing it out of spec when new...or did they mess up the "16" on the label ?

 

[OVERKILL]

Originally Posted By: CATERHAM

But if you're never seeing near that cold it's VI that matters most and for 0W oils viscosity graphs are probably good down to -20C or even -25C.


Any way of substantiating this statement? I mean it rather bold to claim that a viscosity calculator, regularly regarded as being accurate down to ~0C, is somehow accurate for an additional 20-25C with a 0W-xx oil. And given that you used the word "probably" it would seem that you aren't really all that certain of it yourself

 

[Gokhan]

Originally Posted By: CATERHAM
No I said 85C and OP correlates with HTHSV not KV.
83C-93C is the normal operating oil temp's for most engines.
A lower OP reading at the same OT and engine rpm represents a lower operational viscosity.

Your statement highlighted in red is blatantly false. You are the only person who thinks oil pressure is correlated with high-temperature, high-shear viscosity (HTHSV) instead of kinematic viscosity (low-shear viscosity [KV]) as far as I know.

Oil pressure simply results from the laminar flow of oil through oil passages. This is determined by the kinematic viscosity, also known as the low-shear viscosity.

High-shear viscosity on the other hand strictly relates to sliding (shearing) surfaces. It's useful to correlate with the wear protection and fuel economy of the sliding (shearing) parts. It's not useful for relating to the oil flow and pressure, which is a simple fluid flow that is determined by the kinematic (low-shear) viscosity.

In fact, if kinematic viscosity doesn't relate to anything, why do you think that they even bother specifying it? One of the reasons why they make oils such as German Castrol 0W-30 with low KV100 (KV @ 100 C) but high HTHSV is so that you get less oil pressure and more oil flow (smaller KV) while still maintaining the wear protection (larger HTHSV).

Also, when it comes to wear protection, sump temperature of the oil has little meaning. In the bearings, temperature and pressure rises rapidly in the millisecond instant when the oil is rapidly squeezed where the minimum oil-film thickness occurs in the wobbling bearing, easily to around 150 C or more. This is the reason why HTHSV is measured at 150 C but not at the oil-sump temperature. In general, oil temperature will simply be higher between sliding parts due to friction than in the sump, where the oil is cooling. Also, piston rings can experience even higher temperatures due to combustion.

Therefore, your oil-pressure readings are of no use in judging either KV100 or HTHSV. It's only useful for judging oil flow at your normal operating oil-sump temperature (80 - 95 C) but nothing more.

 

[Shannow]

Gokhan, I mostly agree with your post above...a lot of what you are saying is actual science, which CATERHAM dismisses as not "feeling right"...e.g. temperature rise across bearings etc.

However, CATERHAM is partly right with oil pressure, and has dismissed my VK100 statement prior in the thread, in that for a given architecture, in a running engine at reasonable revs (shear rate) HTHS is the dominant driver in oil pressure.

If the oil simply pumped through a stationary engine, it would be KV100, however bearings will only allow as much oil in as needs replenishing due to side leakage, and side leakage in the pressure zone is related to operational viscosity. The leakage across the "wide" oil feed part is kinematic...but HTHS, when the bearings are moving quickly is the main driver.

e.g. this bloke has done a decent job. Note the abnormally high oil temperature of 95C, which as I've learned here is beyond what most engines run at.

http://www.itinerant-air-cooled.com/viewtopic.php?f=46&t=8721

Which is interesting, as he shows TGMO with a 2.6 HTHS, which quickly shears out of grade (so much for the 20s don't shear out of grade).

Shows that HTHS is the main part of the oil pressure equation, and also demonstrates that Toyota don't need to aim for infinite VI, when they are basing their game on marginal HTHS...the extra KV100 that they gain just wastes energy on the part of the system that runs in the first newtonian period.

Note, while I agree with CATERHAM's Oil Pressure/HTHS assertion for the architecture being tested (squirters, chain oilers, etc. all skew the balance...I disagree vehemently with his assertion that oil pressure equals protection.

 

[Gokhan]

Thanks for linking to CATERHAM's data.

No, I still do not agree with him.

Oil pressure directly relates neither to HTHSV nor to KV100.

Oil pressure directly relates to KV at the operating temperature, which is about 85 C, and the oils with the highest VI and/or lowest KV40 will have the lowest oil pressure.

His data is actually misleading because what he is seeing is an indirect correlation with HTHSV. It's only showing us that KV85 is somehow better correlated with HTHSV than with KV100. Since oil pressure is correlated with KV85, which is somehow correlating well with HTHSV in the oils he studied, he's coming to the wrong conclusion that oil pressure is determined by HTHSV.

 

[Gokhan]

Perhaps CATERHAM could plot the oil pressure vs. KV85. It should be a straighter line than vs. both HTHSV and KV100.

 

[Gokhan]

I see he tested at 95 C.

Here is an example:

TGMO 0W-20 SM KV95 = 11.3 cSt
RL 5W-20 SN KV95 = 12.7 cSt
(KV95 linearly interpolated from KV100 and KV40.)

TGMO 0W-20 SM HTHSV = 2.6 cP
RL 5W-20 SN HTHSV = 3.0 cP

Measured TGMO 0W-20 SM OP = 71 psi

Calculated RL 5W-20 SN OP using KV95 = 71*12.7/11.3 = 80 psi
Calculated RL 5W-20 SN OP using HTHSV = 71*3.0/2.6 = 82 psi

Measured RL 5W-20 SN OP = 80 psi

So, the oil pressure at 95 C calculated using the KV95 is right on the money. The oil pressure calculated using the HTHSV is quite off.

KV100 correlates poorly with oil pressure because the oils studied have dramatically different viscosity indices and their KV100 poorly correlates with their KV95 as a result.

It's not the HTHSV that determines the oil pressure. It's the KV85, KV95, or KV at whatever operating temperature the oil pressure is measured.

 

[Shannow]

Originally Posted By: Gokhan
TGMO 0W-20 SM KV95 = 11.3 cSt
(KV95 linearly interpolated from KV100 and KV40.)


There's your first mistake, it can only be linearly interplated on a log graph, which makes it 9.5(ish) at 95C...

I won't continue with the rest of the refutation, as such a simple error early on throws the whole argument out the window, and by linearly interpolating a logarithmic function, you are creating straight lines where none exist.

 

[Gokhan]

Originally Posted By: Shannow
Originally Posted By: Gokhan
TGMO 0W-20 SM KV95 = 11.3 cSt
(KV95 linearly interpolated from KV100 and KV40.)

There's your first mistake, it can only be linearly interplated on a log graph, which makes it 9.5(ish) at 95C...

I won't continue with the rest of the refutation, as such a simple error early on throws the whole argument out the window, and by linearly interpolating a logarithmic function, you are creating straight lines where none exist.

Fair criticism.

However, it wasn't really a mistake but an approximation. For small changes in temperature, you can approximate an exponential dependence with linear dependence.

Nevertheless, you're certainly right that the error in that linear approximation is too big.

Therefore, I provided this Excel sheet to calculate the viscosity as a function of temperature. Simply plug in KV40, KV100, and T, and you will get KV @ T using a simple two-point exponential fit. You can download the excel file or copy it to your own Google Drive:

Oil viscosity vs. temperature calculator (spreadsheet)

Note: KV = a*exp(-b*T), with two coefficients a and b calculated as first b = (ln(KVT1)-ln(KVT2))/(T2-T1) and then a = KVT1*exp(b*T1)

I don't have the KV40 and KV100 data for RL 5W-20 SM, which is thicker than the SN version. So, I can't really compare it against the TGMO 0W-20 SM.

CATERHAM, perhaps you can plot the oil pressure vs. KV95 using the KV95 values from the spreadsheet calculator I provided. You need to provide the KV40 and KV100 values for the oils you studied.

Note that CATERHAM claims that all 0W-20 oils have approximately HTHSV = 2.6 cP. However, he then says that TGMO 0W-20 SN results in an oil pressure 6 - 8 psi less than others. If his claim that oil pressure is determined by HTHSV was correct, TGMO would then have to have the same oil pressure as the others. Also, if oil pressure is determined by HTHSV, you wouldn't see any temperature effects when you change the operating temperature. In reality, you should see big temperature effects because of the differences in viscosity indices.

Again, I am pretty confident that oil pressure is determined by KV @ T where T is the oil temperature the oil-pressure readings are taken.

 

[Shannow]

Go to
Google Book Result

Figure 1 shows the shear rates within IC engines.

Clearly the bearings are operating in a High shear regime, and will be if anything in the second Newtonian phase of the curve for multigrades...which makes the HS the appropriate viscosity to talk about...true monogrades, it's meaningless, as they are Newtonian.

The shear rates in the oil galleries are applicable to the KV100 (or KV93.46), which is my point regarding TGMOP making the KV100/VI too high if their goal truly is economy.

However, CATERHAM is correct that the HS viscosity is the operation viscosity for the bearings...

http://www.bobistheoilguy.com/forums/ubb..._sp#Post3307068

Has HS at 100, which would be better in the testing, but we don't know (some infer) what the "HS" viscosity Index of an oil is...have seen (IIRC Savant labs) paper which has the HS viscosity running below and parallel to the KV...will find it after work if I can.

 

[JAG]

Gokhan,

I like that you performed some analysis since I enjoy such things. I have some comments. You already stated that getting the kinematic viscosities by linearly interpolating is not accurate enough, which I agree with. Your analysis method seems to assume that correlation requires there to be a linear relationship between the oil pressure of one oil and a different oil with the slope of the line being the ratio of the two oils viscosities, whether the viscosity is kinematic at some temperature or the HTHS viscosities. Let OP1 and OP2 be the oil pressures of oil 1 and 2, respectively. Let VIS1 and VIS2 be the viscosities of oils 1 and 2, respectively. Then your method is assuming the following relationship be accurate in order for correlation to be good:
OP2 = VIS2/VIS1*OP1, which is equivalent to OP2/OP1 = VIS2/VIS1. The first equation is the equation of a line with slope of VIS2/VIS1 and a y-intercept of 0.

The fault with that assumption is that correlation does not require a linear relationship. Correlation is determined by how far off the predicted values are from the curve determined by curve-fitting the data. That was shown well in the link that Shannow provided. Note that neither of the fitted curves are straight lines. There was a lot more scatter in the plot using kinematic viscosities compared to the one using HTHS, which means the latter had better correlation. Assuming comparable measurement errors for both, the data using kinematic viscosities indicates that some other viscometric property or properties was/were affecting oil pressure. This other property is widely accepted to be temporary shear. HTHS measurements already account for this, hence the better correlation of OP to HTHS than to kinematic viscosity (for oils that exhibit temporary shear).

 

[Gokhan]

If the bearings are the main resistance to the oil flow, they will be the main contribution to the oil pressure. (This is clearly not the case in old engines where bearings aren't pressurized.) You're right that high-shear viscosity is probably more appropriate for the bearings because of the temporary shear of VII molecules. There are other contributions (paths) to oil flow as well and oil pressure will not entirely be determined by the bearings.

However, there is a big problem. HTHSV is only specified at 150 C. Average temperature of the oil in the bearing will be a lot less. Assuming that the oil pressure correlates with HTHSV150 doesn't take into account any temperature or viscosity-index effects.

In fact, CATERHAM is the one who claims that (1) all 0W-20s have HTHSV150 ~ 2.6 cP and (2) oil pressure is entirely determined by HTHSV. He then says TGMO 0W-20 SN produces 6 - 8 psi less oil pressure than another 0W-20 with the same HTHSV150. This is self-contradictory.

For this reason, a temperature-dependent viscosity is more appropriate in my opinion to judge oil pressure. To me, it looks like TGMO has less oil pressure simply because it's much thinner at 80 - 85 C due to its ultra-high VI than other oils. You can use the spreadsheet I provided above to calculate the viscosity as an exponential function of temperature.

My understanding of HTHSV150 has been that it applies more to high-load situations where the minimum oil-film thickness (MOFT) is very small and the temperature at the MOFT instantaneously reaches 150 C or so due to adiabatic heating from the instantaneously rising pressure. In other words, HTHSV150 is more of a measure of wear protection at extreme conditions than a measure of viscosity for more normal conditions.

 

[Shannow]

Originally Posted By: Gokhan
My understanding of HTHSV150 has been that it applies more to high-load situations where the minimum oil-film thickness (MOFT) is very small and the temperature at the MOFT instantaneously reaches 150 C or so due to adiabatic heating from the instantaneously rising pressure. In other words, HTHSV150 is more of a measure of wear protection at extreme conditions than a measure of viscosity for more normal conditions.


Temperature rise in the oil film is due to the frictional work applied to the oil...adiabatic heating is only applicable to compressible fluids like gasses, not incompressible liquids.

HTHS is an attempt at viscosity measurement under high shear...it would be better carried out at the Walmart spec sheet I posted of 100C than 150C, I agree, but if the fluid is again in the second Newtonian range, HTHS is going to be a much better predictor of the high shear viscosity at 120C than any KV is likely to be.

 

[Blue_Angel]

Another nit-pick:

Originally Posted By: Gokhan
If the bearings are the main resistance to the oil flow, they will be the main contribution to the oil pressure.


If the main bearings are the main resistance to oil flow, they will NOT be the main contributor to oil pressure. The most free-flowing part of the oil flow path will have the largest effect on oil pressure.