Originally Posted by ZeeOSix
Originally Posted by Gokhan
Now, here is the million dollar question: Can an almost-VII-free HTHSV = 3.0 cP 5W-30 oil or even an almost-VII-free HTHSV = 2.6 cP 5W-20 oil made from a high-VI base oil protect against catastrophic wear better than an HTHSV = 4.0 cP oil with a very high VII content and a base-oil with a so - so viscosity index?
So one reason I chose Valvoline Advanced 5W-30 full synthetic is because the HTHSV is 3.2 cP, KV100 is 10.2 cSt, VI = 158 and Noack 9.3%. The VI of 158 and KV100 of 10.2 seems to be on the low end for most 5W-30 full synthetics oils that I compared (ie, Castrol, Pennzoil, Mobil 1). So how does Valvoline Advanced 5W-30 get a relatively high HTSHV with a relatively low VI and KV100 compared to those other 3 brands which all have a HTHSV less than 3.2 and a VI greater than 158.
Originally Posted by oil_film_movies
Originally Posted by ZeeOSix
So one reason I chose Valvoline Advanced 5W-30 full synthetic is because the HTHSV is 3.2 cP, KV100 is 10.2 cSt, VI = 158 and Noack 9.3%. The VI of 158 and KV100 of 10.2 seems to be on the low end for most 5W-30 full synthetics oils that I compared (ie, Castrol, Pennzoil, Mobil 1). So how does Valvoline Advanced 5W-30 get a relatively high HTSHV with a relatively low VI and KV100 compared to those other 3 brands which all have a HTHSV less than 3.2 and a VI greater than 158.
Having a low VI 158 means it has fewer VM polymer chains to get temporary shear during the high-stress HTHS conditions, hence the slightly higher HTHS 3.2. That's it.
Oronite explains it well:
https://www.oronite.com/products-technology/viscosity-modifiers/default.aspx and look under "temporary and permanent viscosity loss", the + tab down that page.
Originally Posted by ZeeOSix
oil_film_movies ... thanks for the link, good info.
We can attempt to answer ZeeOSix's question using my base-oil/HTHSV calculator.
https://www.bobistheoilguy.com/foru...erature-full-shear-viscosity#Post5113871
I plugged in the values from the Valvoline PDS and fine-tuned some of the HTHSV values to three significant figures or more rather than the two reported -- one of the strengths of the calculator is that you can determine the HTHSV more accurately if you know the base-oil type.
This is what I got. Note that these are all estimates and subject to error, especially thanks to the PDS data:
Code
Oil HTHSV BO KV100 BO VI relative VII content BO DV150
VAS 0W-16 2.35 cP 6.25 cSt 152 0.64% 2.2 cP
VAS 0W-20 2.68 cP 6.54 cSt 150 1.8% 2.2 cP
VAS 5W-20 2.70 cP 7.86 cSt 145 0.23% 2.6 cP
VAS 5W-30 3.225 cP 8.31 cSt 144 1.7% 2.7 cP
VAS 10W-30 3.20 cP 6.81 cSt 118 4.3% 2.2 cP
The results are suggesting that all VAS grades except the 10W-30 are made of Group III+++ base oils with extremely high VI and contain very little VII. 10W-30 on the other hand is made from a low-quality Group III with a minimal VI and contains more VII. This makes sense because otherwise, it would classify as a 5W-30, not 10W-30, since higher VI base stocks have lower CCS.
Also note that VAS 5W-20 and VAS 5W-30 have extremely high base-oil dynamic viscosity at 150 °C (BO DV150) because of the high-VI base oil and low VII content.
Shell makes the so-called XHVI (extra-high viscosity index) base stocks. In fact, XHVI seems to be a form of GTL made in Bintulu, Malaysia. However, the KV100 = 8.3 cSt XHVI base stock has Noack = 5%, which doesn't agree with the Valvoline PDS. So, perhaps they sourced some very high VI Group III+++ base stocks from another company.
https://prodepc.blob.core.windows.net/epcblobstorage/GPCDOC_GTDS_XHVI_5.2.pdf
https://prodepc.blob.core.windows.net/epcblobstorage/GPCDOC_GTDS_XHVI_8.2.pdf
To me it looks like the magic here is that Valvoline chose to use an 8 cSt Group III base stock with an extremely high VI for their VAS 5W-20 and VAS 5W-30. Normally an 8 cSt base stock may not be capable of making a 5W-xx oil because of its CCS @ -30 °C may be to high but these Group III+++ and GTL base stocks with very high VI have very low CCS values.
If my estimates are correct, Valvoline Advanced Synthetic 5W-20 and 5W-30 easily win over all other oils in terms of the viscosity performance: extremely high VI base oil, very high base-oil viscosity at 150 °C, and very low VII content.