Automated calculator for the A_Harman index, VII content, and base-oil viscosity

[ZeeOSix]

Originally Posted by OilUzer

I now have a couple of big picture type of questions and/or issues: 1- Based on your info, I am thinking hths would be a useless parameter since its not a true representation of what's going on. So why is it published and/or talked about so much in the industry? 2- At the same time, I am thinking why would an intermediate measurement (htfs) prior to added vii be of a more importance than a final (after added vii) measurement? Basically it sound like throw hths in garbage No?

The machines that measure the shear viscosity are measuring the oil in it's final formulation, so it seems like a valuable measurement. It's still a good comparitive parameter between oils if that's all you got. Notice in the chart Gokhan posted above that the HTFS is at a much higher shear rate than where the HTHS is measured at - a higher shear rate "fully aligns" the VII additives and therefore lowers the temporary viscosity. May only be applicable to certain moving regions in the engine (ie, rings, valve train)

 

[Gokhan]

Originally Posted by OilUzer

I now have a couple of big picture type of questions and/or issues: 1- Based on your info, I am thinking hths would be a useless parameter since its not a true representation of what's going on. So why is it published and/or talked about so much in the industry? 2- At the same time, I am thinking why would an intermediate measurement (htfs) prior to added vii be of a more importance than a final (after added vii) measurement? Basically it sound like throw hths in garbage No?

1. HTHS applies to (a) the wear protection of the bearings and therefore (b) the fuel economy, as the bearings have the main friction losses. 2. HTFS applies to the wear protection of the valvetrain, timing chain, piston rings, and cylinder liners. The VII mostly or fully shears in these parts and hence has an insignificant contribution to the viscosity. HTHS and HTFS are obviously not independent. HTFS is the viscosity of the base oil and DDI package before the VII is added. After you add the VII, it increases the viscosity, and therefore if you have a higher HTFS, you will also have a higher HTHS, even though during the HTHS high-shear measurement, the VII partly but not fully shears.

Originally Posted by ZeeOSix

The machines that measure the shear viscosity are measuring the oil in it's final formulation, so it seems like a valuable measurement. It's still a good comparitive parameter between oils if that's all you got. Notice in the chart Gokhan posted above that the HTFS is at a much higher shear rate than where the HTHS is measured at - a higher shear rate "fully aligns" the VII additives and therefore lowers the temporary viscosity. May only be applicable to certain moving regions in the engine (ie, rings, valve train)

Exactly. If the viscometer can apply a shear rate of about 100 million s⁻¹ (s⁻¹ = per second), which is 100 times the shear rate the HTHS is measured at, you will practically measure the HTFS viscosity. Hugh Spikes et al. used a recently introduced viscometer that can do up to 10 million s⁻¹ and did some extrapolation to measure the HTFS, and they experimentally verified that it is indeed equal to the viscosity of the base oil plus the DDI package with the VII undergoing full temporary shear and not contributing significantly to the viscosity. Unfortunately the commercial viscometers can only do 1 million s⁻¹, at which shear rate, the HTHS is measured. This is because of the heat generated at higher shear rates. Given that HTFS is not part of SAE J300 and viscometers capable of more than 1 million s⁻¹ are hard to make, it is unlikely that we will see HTFS commercially measured and reported in the near future. Nevertheless, it would be very nice if they updated SAE J300 and included a second HTHS, such as HTHS7, which reports the viscosity at 10 million = 10⁷ s⁻¹. Then with both the HTHS6 at 1 million = 10⁶ s⁻¹ and HTHS7 at 10 million = 10⁷ s⁻¹, the oil specs and selection can be more solid. For example the OEM's can increase the fuel economy by reducing the HTHS6 requirement (such as from 3.5 cP to 3.0 cP or even to 2.6 cP) but still ensure wear protection by placing an HTHS7 requirement (such as 2.5 cP).

 

[OilUzer]

so the hths of the final product is increased by plastic ... Also an independent lab can measure and verify the hths of the final product but there is no way to measure the htfs since vii have already been added to it. True? you are calculating the htfs based on published data and I see what you mean by garbage in, garbage out. if a lab has a sample of the base oil including the ad pack (prior to addition of vii), I assume they can measure the intermediate hths or htfs as you call it. True? Q: When oil companies sell their base oil to others, do they provide this info? Or if a company is buying a base oil do they ask I need a base oil with hths of for example > 2.2 and < 2.7? Do ad packs have any impact on viscosity and/or hths. Don't they thin down the oil? So if a company buys a base oil with hths of 2.5 and add their own ad pack, I assume the new hths (htfs at that point) will be different (lower?) than 2.5. No?

 

[Gokhan]

Originally Posted by OilUzer

so the hths of the final product is increased by plastic ... Also an independent lab can measure and verify the hths of the final product but there is no way to measure the htfs since vii have already been added to it. True? you are calculating the htfs based on published data and I see what you mean by garbage in, garbage out. if a lab has a sample of the base oil including the ad pack (prior to addition of vii), I assume they can measure the intermediate hths or htfs as you call it. True? Q: When oil companies sell their base oil to others, do they provide this info? Or if a company is buying a base oil do they ask I need a base oil with hths of for example > 2.2 and < 2.7? Do ad packs have any impact on viscosity and/or hths. Don't they thin down the oil? So if a company buys a base oil with hths of 2.5 and add their own ad pack, I assume the new hths (htfs at that point) will be different (lower?) than 2.5. No?

The detergent-dispersant-inhibitor (DDI) package (additive package) acts like a viscosity-index improver (VII) that does not shear-it significantly increases both the viscosity and viscosity index (VI). See the Hugh Spikes et al. paper for details. As I said in my previous post, if you have the viscometer Hugh Spikes et al. used, you can measure both the standard HTHS6 at 1 million = 10⁶ s⁻¹ (per second) and HTHS7 at 10 million = 10⁷ s⁻¹, the latter of which would approximate the HTFS. Hugh Spikes et al. used extrapolation from various shear rates up to the 10⁷ s⁻¹ value their viscometer allows to get the actual HTFS, which is typically reached at 10⁸-10⁹ s⁻¹. Yes, you can also measure the HTHS6 (or even the low-shear viscosity at 150 °C if the base oil and DDI package are shear-stable) of the base oil and DDI package before you add the VII, which would practically be the HTFS, except the viscosity of the oil solvent used in the packaged VII and the small density change arising from the addition of the VII would slightly alter it in the VII-blended-in oil. The base-stock specs sometimes include the HTHS (HTHS6). However, they often only include the density, KV40, and KV100, and it is the blender's task to get the finished KV40, KV100, and HTHS (HTHS6) right when they blend in the DDI package and VII. Moreover, as I said the DDI package significantly increases the KV40, KV100, VI, and HTHS (HTHS6) before you blend in the VII.

 

[LubricatusObsess]

Thanks, Gokhan! I get it now - the shear RATE is the important thing. High shear rates reduce base oil viscosity somehow. Hmmm. Interesting discussion with a lube manufacturer overnight revealed Shell is using a newer "star" VII molecule additive that does not temporary shear or chop up like conventional "coil" VII molecule. This would help both numbers - HTHS & HTFS viscosities and resultant higher oil film thickness. Which is another reason I've switched from Mobil to Shell for most engine oils. GTL base stocks is another reason. I keep my machines for a long time.

 

[Gokhan]

Originally Posted by LubricatusObsess

Thanks, Gokhan! I get it now - the shear RATE is the important thing. High shear rates reduce base oil viscosity somehow. Hmmm. Interesting discussion with a lube manufacturer overnight revealed Shell is using a newer "star" VII molecule additive that does not temporary shear or chop up like conventional "coil" VII molecule. This would help both numbers - HTHS & HTFS viscosities and resultant higher oil film thickness. Which is another reason I've switched from Mobil to Shell for most engine oils. GTL base stocks is another reason. I keep my machines for a long time.

The shear rate reduces the finished-oil viscosity toward the base-oil (plus the DDI package) viscosity. The base oil and DDI package are usually almost ideal Newtonian fluids. Oh, no, star VII's have been around forever and you don't want them in your engine! Most oil blenders don't use them anymore because they are not thermally stable and leave engine and turbocharger deposits. Oils usually can't pass the GM dexos1 etc. turbocharger tests with star VII's. OCP is the preferred VII type these days because of its exceptional thermal stability, despite being less shear-stable. I would be surprised if Shell used star VII's in their PCMO, even though they are still used in HDEO because the viscosity and shear stability is more important for the heavy-duty diesel engines. Moreover, I am not sure if Shell's Qatar Pureplus GTL is the best GTL out there. Sasol may be making better GTL (lower Noack, lower CCS, higher VI, and higher oxidation stability) and says it costs no more to make GTL than Group I dino base oil. I've seen Super Tech etc. using GTL lately, and they might be buying it from Sasol. Mobil 1 claimed in an internal document that Shell's PurePlus GTL base oil has not improved in oxidation resistance over its previous Group III+ base oil. Don't forget that GTL is a Group III+ base oil, and Group III+ base oils vary greatly in quality regardless of the feedstock being petroleum or natural gas.

 

[OilUzer]

Gokhan, Thanks for responding to all my question. Let's assume your data is %100 correct and has been verified as I don't have any expertise in this field. Now that I better understand your data, my final question is how do these numbers correlate to real wear or deposits numbers short of any (I assume) real tests? Let's say I selected a few 5W30's with "less wear" in mind and i compare the top %10 to the bottom %10 from your table. how does that translate to how significant or insignificant the wear is? Considering that the oils meet the manufacturer spec. do you see what I mean? Don't get me wrong I love any additional info/data including your table ... when I am buying some products, I check the reviews but if one scored 9.9 out of 10 and another scored 9.1, I consider both very good and have no problem getting either product.

 

[LubricatusObsess]

I'm getting pretty confused. What was the VII polymer trumpeted not too long ago, then? I will share that star VII polymer was endorsed by a very knowledgeable lube mfg. How can it be both great and terrible? What is OCP? I never understood why GTL is API Group III base stock. Mobil taught us in the world of PAO (now Group IV) they were made from ethylene gas which was derived from methane. Reacted in a hydrotreater to truncate the linear hydrocarbon at desired length (viscosity). Mobil made 3 or 4 base PAO stocks, blended to fit product spec. How can GTL not be API Group IV? Mobil fought against hydrocracking being called "synthetic". Too many marketing games.

 

[Gokhan]

Originally Posted by OilUzer

Gokhan, Thanks for responding to all my question. Let's assume your data is %100 correct and has been verified as I don't have any expertise in this field. Now that I better understand your data, my final question is how do these numbers correlate to real wear or deposits numbers short of any (I assume) real tests? Let's say I selected a few 5W30's with "less wear" in mind and i compare the top %10 to the bottom %10 from your table. how does that translate to how significant or insignificant the wear is? Considering that the oils meet the manufacturer spec. do you see what I mean? Don't get me wrong I love any additional info/data including your table ... when I am buying some products, I check the reviews but if one scored 9.9 out of 10 and another scored 9.1, I consider both very good and have no problem getting either product.

You can't tell how an oil will perform in a benchtop engine wear test or a field test based on HTFS (BO DV150) alone because there are so many other factors, such as the detergent and antiwear additives used. However, it is a very important factor, probably the most important factor given that the detergent and additives used are usually but not always state-of-the-art. There are also many different engine wear tests for different applications. It's the same for the VII content (A_Harman index)—a high-quality oil with a high VII content can leave less engine and turbocharger deposits than a monograde oil with no VII content at all. It looks like the Mobil 1 V-Twin 20W-50 is the HTFS champion in my table (excluding a SAE 50 monograde, which seems to have a slightly inaccurate HTHS). Its HTFS ~ 5.0 cP is higher than the HTHS of most multigrades. Its VII content is low, too. You probably need a very high HTFS in a motorcycle engine.

 

[kschachn]

Originally Posted by LubricatusObsess

I never understood why GTL is API Group III base stock. Mobil taught us in the world of PAO (now Group IV) they were made from ethylene gas which was derived from methane. Reacted in a hydrotreater to truncate the linear hydrocarbon at desired length (viscosity). Mobil made 3 or 4 base PAO stocks, blended to fit product spec. How can GTL not be API Group IV? Mobil fought against hydrocracking being called "synthetic". Too many marketing games.

It is not marketing games at all. This shows that you (like many others on this site) do not understand the reason for group designations in the first place. API 1509 Annex E is titled "API BASE OIL INTERCHANGEABILITY GUIDELINES FOR PASSENGER CAR MOTOR OILS AND DIESEL ENGINE OILS" and defines the criteria for base oil interchangeability for blenders. These criteria are clearly spelled out in that document and if you read them you will see how and why GTL base stocks are Group III. I would have thought that being an industry insider you would know how this Annex is used and why it exists. It clearly cannot be Group VI given that the definition for that Group is:

Quote

Group IV base stocks are polyalphaolefins (PAO). PAOs can be interchanged without additional qualification testing as long as the interchange PAO meets the original PAO manufacturer's specifications in physical and chemical properties.

Group designations are not about how the material is obtained or synthesized:

Quote

A base stock is a lubricant component that is produced by a single manufacturer to the same specifications (independent of feed source or manufacturer's location); that meets the same manufacturer's specification; and that is identified by a unique formula, product identification number, or both. Base stocks may be manufactured using a variety of different processes including but not limited to distillation, solvent refining, hydrogen processing, oligomerization, esterification, and rerefining.

Again with you being an industry insider I am surprised you do not know this.

 

[ZeeOSix]

Originally Posted by Gokhan

It looks like the Mobil 1 V-Twin 20W-50 is the HTFS champion in my table (excluding a SAE 50 monograde, which seems to have a slightly inaccurate HTHS). Its HTFS ~ 5.0 cP is higher than the HTHS of most multigrades. Its VII content is low, too.

I know you're just picking the champ in the whole table. but It would only be fair to compare like viscosities ... ie, xW-20 to xW20, xW-30 to xW-30, etc. Just like comparing HTHS to each other .,.. the viscosity has a huge factor in the HTSH or HTFS.

 

[LubricatusObsess]

kschachn - I no longer am an industry insider - I left Mobil Oil circa 1990 as the buyout rumors swirled, as I said many others did as well. I only read about the great Mobil vs. Castrol fight over what a synthetic was, the result, and API's grouping of molecules. Otherwise I wouldn't be asking these questions, right? Isn't that what this site is for? Questions and sharing information? Based on many of the postings I'm seeing, it is turning into a contest of who has the most current knowledge. That's not what this site used to be.

 

[Gokhan]

Originally Posted by LubricatusObsess

I'm getting pretty confused. What was the VII polymer trumpeted not too long ago, then? I will share that star VII polymer was endorsed by a very knowledgeable lube mfg. How can it be both great and terrible? What is OCP?

First of all permanent shear is an entirely different phenomenon than temporary shear, the latter of which the A_Harman index measures and the HTFS (BO DV150) takes into account. High permanent shear does not mean high temporary shear and vice versa. Hugh Spikes et al. paper linked above is a tour de force discussion of temporary VII shear. In permanent shear the VII molecules are permanently deformed or broken under very high shear rates such as in the valvetrain and timing chain and no longer contribute to the viscosity even after the shear rate goes back to zero. In temporary shear the VII molecules temporarily and either partially or fully align themselves with the flow, temporarily reducing or eliminating their contribution to the viscosity. Once the shear rate is reduced to a low shear rate, their shapes are not altered from the original and they fully contribute to the viscosity. What the tech-support guy told you about the hydrogenated-styrene star VII is permanent shear, not temporary shear. These star VII's are high-(permanent)-shear-stable but low-thermally stable, i.e. dirty, VII's. They retain their viscosity boost well in the long run, but they form more engine and turbocharger deposits, as they run dirty. They are more popular in HDEO application, where viscosity and permanent-shear stability is more important than engine deposits. On the other hand, olefin copolymer (OCP) linear VII's are mid-(permanent)-shear-stable but high-thermally stable, i.e. clean VII's. They experience moderate permanent shear, but they run much cleaner. They are very popular in high-performance PCMO applications as well as most other PCMO applications as a result. I discussed a nice article about the deposits caused by star and OCP VIIs: GM turbocharger test: No correlation for deposits with TEOST 33C or moly

Originally Posted by LubricatusObsess

I never understood why GTL is API Group III base stock. Mobil taught us in the world of PAO (now Group IV) they were made from ethylene gas which was derived from methane. Reacted in a hydrotreater to truncate the linear hydrocarbon at desired length (viscosity). Mobil made 3 or 4 base PAO stocks, blended to fit product spec. How can GTL not be API Group IV? Mobil fought against hydrocracking being called "synthetic". Too many marketing games.

Group IV is synonymous with PAO, which is a laboratory-synthesized base oil. You can't classify any other base oil under Group IV, but all other laboratory-synthesized base oils are classified under Group V. GTL is a hydrocarbon-based base oil, and it is classified under Group III—Group III+ to be more precise. The main difference between the petroleum-based traditional Group III and natural-gas-based GTL Group III is the feedstock—petroleum-derived slack wax vs. natural-gas-derived wax, respectively. The rest of the process involves either catalytic or solvent dewaxing and a lot of hydroprocessing, which is also the same for Group II. The quality of the base oil depends on the severity of the hydroprocessing, which decreases both the CCS and Noack and increases the viscosity index (VI). As the process becomes more severe, you go from Group II to II+, III, III+, III++, III+++, III++++, and so on. The higher the group, the more the oxidation resistance the base oil has, which results in longer OCI's and cleaner engines. Therefore, not all GTL base oils are equal, and Sasol is competing with Shell. Sasol says, with the GTL technology, a Group III+ base oil can be made as cheap as a Group I base oil (highly refined mineral oil (dino base oil)). The processes after "waxy lube oils" should be the same for Group II, Group III, and GTL: This is the same as above, except solvent dewaxing is replaced by catalytic dewaxing, which is what Shell uses in its Pearl, Qatar GTL plant:

 

[Gokhan]

ISOCRACKING® (hydrocracking), ISODEWAXING® (catalytic dewaxing), and ISOFINISHING® (hydrofinishing) processes of the Chevron Lummus Global's hydroprocessing system, which can be used to make Group II, Group II+, Group III, and Group III+ base oils is explained at the link below. A similar process is also used to make GTL base oil, which uses the same catalytic-dewaxing and hydrofinishing steps for a natural-gas-derived wax instead of a petroleum-derived wax. Hydroprocessing: Chevron Lumus Global base oils The point is that Group II, Group II+, Group III, Group III+, and GTL base oils are made through the same process, and the quality depends not only on the feedstock (petroleum-derived wax or natural-gas-derived wax) but also largely on the severity of the processing.

 

[Direct_Rejection]

My New Motor Oil High Performance Lubricants HPL HD 0W16 0.8555 density at 60 degrees F 38.86 KV 40 7.16 KV 100 150 VI 2.428 HTHS minimum 13.5 TBN

 

[Gokhan]

Originally Posted by Direct_Rejection

My New Motor Oil High Performance Lubricants HPL HD 0W16 0.8555 density at 60 degrees F 38.86 KV 40 7.16 KV 100 150 VI 2.428 HTHS minimum 13.5 TBN

Nice oil. My calculator is showing HTFS = 2.1 cP, which is much higher than that of the M1 AFE 0W-16 and PP 0W-16, and VII = 1.7%, which is much lower than that of those mentioned. The TBN is very strong.

 

[Direct_Rejection]

Originally Posted by Gokhan

Originally Posted by Direct_Rejection

My New Motor Oil High Performance Lubricants HPL HD 0W16 0.8555 density at 60 degrees F 38.86 KV 40 7.16 KV 100 150 VI 2.428 HTHS minimum 13.5 TBN

Nice oil. My calculator is showing HTFS = 2.1 cP, which is much higher than that of the M1 AFE 0W-16 and PP 0W-16, and VII = 1.7%, which is much lower than that of those mentioned. The TBN is very strong.

Thank you for the calculations and comments Gokhan ! These dudes at HPL are dialed in. Much thanks to David Ward for taking the time to go into detail. And to Mary Jane at Advanced for great support. It sounds like HPL uses best of the best Chevron ingredients, if that helps in figuring out base stock composition. They spend a lot of time testing different blends, to come up with ideal formulas. For the Thickies, HPL makes a Heavy Duty 20W40 that looks compelling. They also produce an SP rated line, and Racing oils. HPL has some serious fleet accounts too. I will use this HD 0W16 with great confidence.

 

[bulwnkl]

I've lost track of which threads are what, so I'm asking here: Gokhan, Why do you suppose that HPL's SAE 20 has noticeable VII in it? Related: Why do you suppose their 10W20 has essentially none? Those things are what your spreadsheet claims, anyway.

 

[Gokhan]

Originally Posted by bulwnkl

I've lost track of which threads are what, so I'm asking here: Gokhan, Why do you suppose that HPL's SAE 20 has noticeable VII in it? Related: Why do you suppose their 10W20 has essentially none? Those things are what your spreadsheet claims, anyway.

Obviously for a monograde oil, A_Harman index ~ 1 and VII = (1−A_Harman index) ∕ 2 ~ 0. HPL PCMO 20W-50 has VII ~ −3%, which is also obviously wrong. HPL PCMO 10W-20 is probably also a SAE 20 monograde. There are two possible explanations: 1. Specs of HPL oils significantly vary from batch to batch, and they used different batches to test for KV and HTHS. This would explain why some HPL monogrades have VII ~ 0 as expected, while others don't make sense. You need to use the same batch for KV and HTHS for the calculation to work. 2. ASTM D341 viscosity extrapolation fails for some of the base oils used in HPL oils. Normally ASTM D341 works very well for a monograde oil without a VII. However, for some PAO base oils, especially mPAO base stocks HPL uses, it's not clear how well ASTM D341 works.

 

[bulwnkl]

Thanks for the reply