Originally Posted by Ignatius
@Gokhan I read though your list linked here:
https://www.bobistheoilguy.com/foru...erature-full-shear-viscosity#Post5133467
Do you have any info on the VII on Rotella Gas Truck 0w-20 specifically? There is a huge difference between RGT 5w-20 (being among the lowest VII) and RGT 5w-30 (being among the highest VII) among those listed on your spreadsheet.
I am curious to know where RGT 0w-20 stands comparatively speaking.
The problem with Shell is that they don't provide HTHS in their data sheets, which makes my VII and base-oil viscosity estimates a guesswork.
I played around with it to see which HTHS value is more reasonable. To keep things in line for the
base-oil viscosity index, which is actually not a reliable calculation because the VII type and how the VII scales the viscosity with the temperature is unknown (I assume a constant scaling, which is usually reasonable for OCP VII),
I had to increase HTHS for RGT 5W-30 to 3.2 cP. So, perhaps RGT 5W-30 indeed has a high HTHS by design. This also decreases the VII content estimate for it and makes it more reasonable.
If someone can contact Shell and find out the actual HTHS values for RGT 0W-20, 5W-20, and 5W-30, I can run a more reliable calculation. If RGT 5W-30 indeed has HTHS = 3.2 cP, this would be a major, major verification for my calculation, as estimating HTHS goes a step beyond the original scope of my calculation.
Meanwhile, these are my latest estimates:
Estimated VII content and base-oil viscosity for selected oils
