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

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Originally Posted by 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.
Hello Gokhan, I can answer some of these questions for you but at the same time I will leave you with another. We do not calculate anything we publish on our data sheets. We have all of the instruments in-house required for SAE J300 and publish what we measure. We absolutely use the same batch of oil for all of the testing. It would be bad lab discipline to do otherwise. You are correct that both our SAE 20 as well as our 10W20 are monogrades with no VI Improver. What we are experiencing is a real but not yet explained synergy in our formulation. We have repeated the tests (again with the same batch) ant the results repeat. We have run the standards through our instruments to verify the calibration another are right on the money. There definitely is a discrepancy from D-341 vs what we are actually measuring. So the real question is what is the synergistic relationship that is working in our favor? I cannot yet answer that question but it does repeat in our lab. David
 
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Gokhan, Thank you for asking about the PCMO 20W50 published on our PDS. We ran the tests again on that oil and everything repeated except the HTHS. We then ran HTHS across the range of products and the HTHS did repeat. For whatever reason we did not get the correct result initially when running that product. Providing truthful and accurate data is important to us. I appreciate that your calculation project did trap this error and you shared that with us. We will correct that value on our PDS so you will have the correct data for your spreadsheet. David Ward
 
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Just ordered that book by Dr. Leslie R. Rudnick . I figured everyone can use nearly a thousand pages of light technical reading.
 
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Working with Les I can vouch that he has a legitimate passion to do his part to maintain the information available in our field. He spends countless hours on these books. It is a valuable contribution to our industry. Les is one of the smartest people I have ever met and a true gentleman at the same time.

David Ward
 
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