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

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One of the spreadsheet inputs is HTHS viscosity. I can't find this published on Shell Technical Data Sheets. Where can one find this property?
 
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Thanks Gokhan! I really like comparing oils using your spreadsheet. Now is even easier. I wish we had more information from the manufacturers, not all share values like HTHS.
 

Gokhan

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Originally Posted by LubricatusObsess
One of the spreadsheet inputs is HTHS viscosity. I can't find this published on Shell Technical Data Sheets. Where can one find this property?
Unfortunately Shell rarely publishes HTHS. You can only guess it, such as 2.6 cP for a 0W-20 and 3.0 cP for an ILSAC 5W-30. PS: Another thing you can try is to calculate the base-oil viscosity index BO VI in an online calculator such as Widman's using the auxiliary BO KV40 and BO KV100 outputs in the last two columns. You can then manually adjust the HTHS so that BO VI ~ 140 - 145 for Shell's PurePlus GTL base oil. However, BO KV40 and KV100 are often not accurate at all because the VII type is unknown and I assumed a temperature-independent VII viscosity boost (correct for some OCP VII's); so, be cautioned that these last two auxiliary columns are not very reliable and can often be only very rough estimates. By the way this is exactly what I did with the three Quaker State Ultimate Durability oils in my spreadsheet!
 
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Gokhan, I have a question. honestly it's not a trick question. If your target audience are the experts, tribologists, etc. I can understand that and you don't have to answer my question. They probably get turned on by analyzing theses kind of data and research ... grin2 Some background info: As an average oil uzer, I was wondering how to best utilize this info. That's why for example i asked earlier for a ranking column to make it easier for me to get to the bottom of it without crunching too much data. Back to my question and please put on your average user's hat: How do you yourself use the data (i.e. the 3 output columns in your .xlsx) to select an oil? Let's assume you want a 5W30 and find a few that meet the recommended spec. Do you select the best rank from your table or anything within the top %x e.g. %10-20? Thanks
 

Gokhan

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Originally Posted by OilUzer
How do you yourself use the data (i.e. the 3 output columns in your .xlsx) to select an oil?
  • For less engine wear, you want to maximize the HTFS = BO DV150 (not the HTHS, even though the two are related).
  • For less engine and turbocharger deposits, a smaller effective VII content (= a larger A_Harman index) might help.
  • For better fuel economy, you want to minimize the HTHS and also maximize the effective VII content (= minimize the A_Harman index), in other words minimize both the HTHS and HTFS, which also means maximizing the viscosity index VI since you're maximizing the VII content. Therefore, minimizing the engine wear and maximizing the fuel economy contradict each other.
So, basically pick an oil with a high HTFS viscosity (= BO DV150) to help reduce the engine wear. I don't think there is a need to run a 15W-40 with a very high HTFS unless the engine is prone to wear, and most people would be OK with the recommended viscosity, and they can have an extra degree of assurance against wear by picking an oil of a given OEM recommendation with a higher HTFS (= BO DV150). That's about it.
 

Gokhan

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Last but not least, in order for the estimated values in the spreadsheet calculator to be accurate, the values provided by the oil product datasheets must be accurate. However, they are often <span style="font-style: italic"><span style="font-weight: bold">not</span></span>, for example when tested by the PQIA. Therefore, it's not uncommon to have <span style="font-style: italic"><span style="font-weight: bold">"garbage in, garbage out"</span></span> situations when you rely on oil product datasheets.
 
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Originally Posted by Gokhan
Originally Posted by OilUzer
How do you yourself use the data (i.e. the 3 output columns in your .xlsx) to select an oil?
  • For less engine wear, you want to maximize the HTFS = BO DV150 (not the HTHS, even though the two are related).
  • For less engine and turbocharger deposits, a smaller effective VII content (= a larger A_Harman index) might help.
  • For better fuel economy, you want to minimize the HTHS and also maximize the effective VII content (= minimize the A_Harman index), in other words minimize both the HTHS and HTFS, which also means maximizing the viscosity index VI since you're maximizing the VII content. Therefore, minimizing the engine wear and maximizing the fuel economy contradict each other.
So, basically pick an oil with a high HTFS viscosity (= BO DV150) to help reduce the engine wear. I don't think there is a need to run a 15W-40 with a very high HTFS unless the engine is prone to wear, and most people would be OK with the recommended viscosity, and they can have an extra degree of assurance against wear by picking an oil of a given OEM recommendation with a higher HTFS (= BO DV150). That's about it.
So I grabbed the Valvoline Advanced Full Synthetic section from your table - see below. Looking at the HTFS = BO DV150 column, it's happens to be rating them from low to high HTFS, with the 5W-30 giving the largest HTFS value. So is it the higher VII Content in the 10W-30 that is lowering its HTFS? It looks like the 5W-20 would protect better for wear than the 10W-30 since its HTFS is greater than the 10W-30. What other basic "summary information" can be concluded from comparing this group of oils to each other? [Linked Image]
 
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That is strange - if higher HTFS is indicative of higher VII additive, why would the 5W-30 have an HTFS of 2.73 and 5W-20 an HTFS of 2.51? How could 5W-30 have less VII additive than 5W-20?
 
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Originally Posted by LubricatusObsess
That is strange - if higher HTFS is indicative of higher VII additive, why would the 5W-30 have an HTFS of 2.73 and 5W-20 an HTFS of 2.51? How could 5W-30 have less VII additive than 5W-20?
I think the VII amount also needs to be looked at relative to the base oil. Higher VII doesn't automatically mean higher HTFS, as can be seen with the 0W-16 and 0W-20 which have the highest VI. The 5W-30 has more VII additve % than 5W-20 per the table. I think a KV100 having the least VII is what gives a better HTFS. Multiple factors going on.
 

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Originally Posted by LubricatusObsess
That is strange - if higher HTFS is indicative of higher VII additive, why would the 5W-30 have an HTFS of 2.73 and 5W-20 an HTFS of 2.51? How could 5W-30 have less VII additive than 5W-20?
No, HTFS is not indicative of the VII content. HTFS only depends on the base oil and nothing else. It does not depend on the VII. It is the dynamic base-oil (plus the detergent - dispersant - inhibitor (DDI) package) viscosity at 150 °C, which is exclusive of the VII. Therefore, it depends on the base-oil KV100, base-oil VI, and density. A_Harman index is indicative of the VII content.
 

Gokhan

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Originally Posted by ZeeOSix
So I grabbed the Valvoline Advanced Full Synthetic section from your table - see below. Looking at the HTFS = BO DV150 column, it's happens to be rating them from low to high HTFS, with the 5W-30 giving the largest HTFS value. So is it the higher VII Content in the 10W-30 that is lowering its HTFS? It looks like the 5W-20 would protect better for wear than the 10W-30 since its HTFS is greater than the 10W-30. What other basic "summary information" can be concluded from comparing this group of oils to each other?
VAS 10W-30 has a lower base-oil viscosity index VI than VAS 5W-30 according to the calculator. (You can calculate it using the last two columns.) In other words VAS 10W-30 uses a lower-quality base oil such as Group III as opposed to a higher-quality base oil such as Group III+ or GTL in VAS 5W-30. Keep in mind that the data in PDS's are not very accurate at all. HTHS probably has at least a ± 0.1 cP error, and KV40 and KV100 likely have significant errors as well. Therefore, consider everything as an estimate only. Valvoline has reformulated its oils. I have now entered both the SN and SP oils in the spreadsheet. Unfortunately Valvoline doesn't seem to be meticulous about its PDS's and there are errors etc. They were also giving the density in lb/gal with only two significant figures in the SN PDS. Their monogrades give 2% error in the VII content, and I am guessing the HTHS and/or KV are inaccurate. Again, use the calculator for estimates only.
 
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remember xWy and y minus x delta ... Less delta doesn't always necessarily mean less vii. amount of needed vii (vm) depends on the base oil as well as delta. I think if the base oil is not very good, it will ultimately result in a higher vii oil. Good base oils will result in a natural higher vi oils with less vii. That's why 0W20 in ZeeOSix example (vs. the 10W30) has a less vii even though both have a delta of 20. That means 0W20 had a better base oil. Kind of makes sense since typically 0W oils require a better base oil dealing with lower temps ... So 10W30 htfs is getting punished by it's base oil per Gokhan ... Whereas it's hths is significantly higher. However, an inferior base oil will require higher vii (amount is delta dependent) . So I am thinking there is some indirect relationship there but Gokhan is saying "htfs only depends on the base oil". Maybe he can elaborate. Anyway I'm just analysing that data and not saying it's wrong or right. Edit: I guess I kind of see what Gokhan means. htfs depends on base oil ... but so does vii. vii also depends on delta. Are you saying htfs is independent of delta?
 
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Thanks for clarifying, Gokhan. Maybe this stuff is over my head. Same as OilUzer, I'm trying to understand how to apply the information. In general, are we looking for a high HTFS viscosity value (high base oil film thickness @ 150C), and high A_Harman Index value for less VII additive (shear-down deposits)? Don't understand why hi temp base oil film thickness is called High Temp "Full Shear"? Base oils aren't sheared in general, are they? Shear is more a concern for the VII additive?
 
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Originally Posted by LubricatusObsess
Don't understand why hi temp base oil film thickness is called High Temp "Full Shear"? Base oils aren't sheared in general, are they? Shear is more a concern for the VII additive?
"Shear" in the context of the "S" in HTHS and HTFS is talking about the viscosity of the oil as it's mechanically sheared (ie, the relative layer movement within the oil film) at the standard test shear rate value - this is known as the "temporary shear". It's not measuring the "permanent shearing" of the oil and VII additives. Any liquid temporarily "shears" when trapped between two moving surfaces. In the standard shear test, it's measuring the temporary oil viscosity as the thin layer if oil at 150 deg C is sandwiched between two moving surfaces to simulate engine parts moving past each other. https://www.savantlab.com/testing-highlights/testing-shear-stability-and-viscosity-loss/
 

Gokhan

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Originally Posted by OilUzer
remember xWy and y minus x delta ... Less delta doesn't always necessarily mean less vii. amount of needed vii (vm) depends on the base oil as well as delta. I think if the base oil is not very good, it will ultimately result in a higher vii oil. Good base oils will result in a natural higher vi oils with less vii. That's why 0W20 in ZeeOSix example (vs. the 10W30) has a less vii even though both have a delta of 20. That means 0W20 had a better base oil. Kind of makes sense since typically 0W oils require a better base oil dealing with lower temps ... So 10W30 htfs is getting punished by it's base oil per Gokhan ... Whereas it's hths is significantly higher. However, an inferior base oil will require higher vii (amount is delta dependent) . So I am thinking there is some indirect relationship there but Gokhan is saying "htfs only depends on the base oil". Maybe he can elaborate. Anyway I'm just analysing that data and not saying it's wrong or right. Edit: I guess I kind of see what Gokhan means. htfs depends on base oil ... but so does vii. vii also depends on delta. Are you saying htfs is independent of delta?
You take a base oil plus a DDI package before you blend in the VII. It will have a certain base-oil KV100 and base-oil viscosity index VI -- before the VII is added. The base-oil viscosity index VI will be higher for higher-quality base oils and higher API group numbers. The HTFS equals to the HTHS before you add the VII. In other words if you measure the HTHS before you add the VII, it will be equal to the HTFS. After you add the VII, both the KV100 and viscosity index VI increase. The HTHS also increases and it is no longer equal to the HTFS.
 
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With Gokhan's permission, I took a shot at filtering his calcs to show oils with two preferential characteristics; 1) Lowest VII additization < 5.0% 2) Highest High Temp Base Oil Viscosity, >3.0 cP I selected the cut point values based on data ranges. Did not use a statistical standard deviation or confidence interval, etc. 12 of the 68 oils on his spreadsheet met both quality criteria. I highlighted those with heavy borderline around the rows. Amsoil, Chevron, and Mobil had the most. [Linked Image]
 

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Originally Posted by LubricatusObsess
Thanks for clarifying, Gokhan. Maybe this stuff is over my head. Same as OilUzer, I'm trying to understand how to apply the information. In general, are we looking for a high HTFS viscosity value (high base oil film thickness @ 150C), and high A_Harman Index value for less VII additive (shear-down deposits)?
  • In the calculator VII content = (1 - A_Harman index) / 2. Therefore, a high A_Harman index means a low VII content.
  • HTFS only depends on the base oil (plus the DDI package). It excludes the VII entirely. A thick base oil with a high base-oil viscosity index VI (the latter because it's measured at 150 °C) will result in a high HTFS.
  • HTHS depends on both the HTFS (base-oil and DDI viscosity) and VII content.
  • You need a high HTFS (high base-oil and DDI viscosity) for less valvetrain, timing-chain, piston-ring, and cylinder-liner wear, as these engine parts experience full temporary shear.
  • Less VII content (higher A_Harman index) might help reduce engine deposits caused by burned VII plastic.
  • We are not talking about permanent shear here. We are talking about temporary shear, which I will explain below.
Originally Posted by LubricatusObsess
Don't understand why hi temp base oil film thickness is called High Temp "Full Shear"? Base oils aren't sheared in general, are they? Shear is more a concern for the VII additive?
The shear in this context refers to the temporary shear of non-Newtonian fluids under high shear rates, which is a temporary viscosity loss that goes away when the shear rate becomes zero. The shear rate is defined as the relative speed of two moving surfaces divided by the thickness of the fluid film separating them. For example if the relative speed is 1 meter per second and the separation is 1 micrometer, the shear rate is 1 million per second, which is the shear rate at which the HTHS is measured. While every base oil is non-Newtonian to some extent, most are almost ideal Newtonian fluids and the temporary shear is negligible. POE base stocks and high-viscosity PAO base stocks are among exceptions as they are significantly non-Newtonian and experience temporary shear. When you add the VII, the oil becomes non-Newtonian. As the shear rate is increased, the VII molecules align themselves with the flow, decreasing their contribution to the viscosity, which is how the temporary shear happens. Unlike permanent shear the fluid completely recovers from temporary shear, with no permanent viscosity loss. The HTHS is measured at a shear rate of 1 million per second and the fractional temporary shear (temporary viscosity loss) at this shear rate is given exactly by 1 - A_Harman index. As you increase the shear rate further, at around 10 - 100 million per second or higher, the VII molecules ultimately fully align themselves with the flow and no longer contribute to the viscosity. The only contribution to the viscosity comes from the base oil and DDI package at these shear rates. Therefore, the oil has undergone "full shear" and the VII has no contribution to the viscosity. The full-shear region is also known as the "second Newtonian phase," where only the Newtonian base oil contributes to the viscosity. The first Newtonian phase is the low-shear region, where the temporary shear doesn't quite start yet. Here is the detailed theory in case you want to learn more: [Linked Image from lh3.googleusercontent.com] [Linked Image from lh3.googleusercontent.com]
 
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Originally Posted by LubricatusObsess
With Gokhan's permission, I took a shot at filtering his calcs to show oils with two preferential characteristics; 1) Lowest VII additization < 5.0% 2) Highest High Temp Base Oil Viscosity, >3.0 cP I selected the cut point values based on data ranges. Did not use a statistical standard deviation or confidence interval, etc. 12 of the 68 oils on his spreadsheet met both quality criteria. I highlighted those with heavy borderline around the rows. Amsoil, Chevron, and Mobil had the most. [Linked Image]
Mostly xW-40 oils, and just a few xW-30 oils. And the xW-30 oils with a higher HTHS and HTFS are on the KV100 thick side for a 30 rating. No surprise there.
 
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Originally Posted by Gokhan
Originally Posted by OilUzer
remember xWy and y minus x delta ... Less delta doesn't always necessarily mean less vii. amount of needed vii (vm) depends on the base oil as well as delta. I think if the base oil is not very good, it will ultimately result in a higher vii oil. Good base oils will result in a natural higher vi oils with less vii. That's why 0W20 in ZeeOSix example (vs. the 10W30) has a less vii even though both have a delta of 20. That means 0W20 had a better base oil. Kind of makes sense since typically 0W oils require a better base oil dealing with lower temps ... So 10W30 htfs is getting punished by it's base oil per Gokhan ... Whereas it's hths is significantly higher. However, an inferior base oil will require higher vii (amount is delta dependent) . So I am thinking there is some indirect relationship there but Gokhan is saying "htfs only depends on the base oil". Maybe he can elaborate. Anyway I'm just analysing that data and not saying it's wrong or right. Edit: I guess I kind of see what Gokhan means. htfs depends on base oil ... but so does vii. vii also depends on delta. Are you saying htfs is independent of delta?
You take a base oil plus a DDI package before you blend in the VII. It will have a certain base-oil KV100 and base-oil viscosity index VI -- before the VII is added. The base-oil viscosity index VI will be higher for higher-quality base oils and higher API group numbers. The HTFS equals to the HTHS before you add the VII. In other words if you measure the HTHS before you add the VII, it will be equal to the HTFS. After you add the VII, both the KV100 and viscosity index VI increase. The HTHS also increases and it is no longer equal to the HTFS.
Ok, I see what you mean. So in case of the 10W30 is ZeeOSix's example, hths was significantly increased after added vii and if I understand you correctly, htfs (much lower than hths) is a better representation of the oil strength. 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 grin2 No?
 
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