Temporary Viscosity Loss

[Gokhan]

Originally Posted by Dak27
Originally Posted by Gokhan
There doesn't seem to be anything special about the Phillips 66 Guardol ECT 15W-40 CK-4, and it has more VII and a thinner base oil than other 15W-40's.

Estimated base-oil viscosity at 150 °C (BO DV150) and VII content of selected oils
Thanks for this chart. Is this the: "A-Harman Base Oil Quality Index" that I've heard a bunch of people here talk about?

Does this pertain only to the finished oil's base, or does it also detail the finished oil's additive pack, along with the base oil?

Thank you in advance!

You're welcome!

A_Harman index, base-oil viscosity at 150 °C (BO DV150 = HTFS (not HTHS)), and VII content estimated by this spreadsheet are different than the base-oil quality index BOQI I have also developed.

What this spreadsheet estimates are the A_Harman index, base-oil viscosity at 150 °C (high-temperature, full-shear viscosity HTFS, directly given by the high-temperature, high-shear viscosity HTHS and A_Harman index) and effective VII content (directly given by the A_Harman index). It does not estimate the base-oil quality or additive-package quality.

The base-oil quality index BOQI ~ 1 (CCS × Noack), not calculated in this spreadsheet, estimates the base-oil quality, related to the API Group number and oxidation resistance of the base oil. It does not estimate the additive-package quality, effective VII content, base-oil viscosity at 150 °C, or A_Harman index.

 

[Koop]

Originally Posted by Gokhan
Originally Posted by Koop
So if I'm understanding this correctly, the temporary viscosity loss is design feature of the CK 4 oil. I have a hard time understanding how this viscosity loss is providing better bearing protection than the CJ 4 which didn't have as much of an oil pressure drop.

No, it has nothing to do with CJ-4 or CK-4. All oils get thinner at higher temperatures, resulting in a lower oil pressure. This is normal behavior.


But, I've observed lower oil pressure under similar loads with CK-4 than I had with CJ-4. That's what has me scratching my head.

 

[Gokhan]

Originally Posted by Koop
Originally Posted by Gokhan
Originally Posted by Koop
So if I'm understanding this correctly, the temporary viscosity loss is design feature of the CK 4 oil. I have a hard time understanding how this viscosity loss is providing better bearing protection than the CJ 4 which didn't have as much of an oil pressure drop.
No, it has nothing to do with CJ-4 or CK-4. All oils get thinner at higher temperatures, resulting in a lower oil pressure. This is normal behavior.
But, I've observed lower oil pressure under similar loads with CK-4 than I had with CJ-4. That's what has me scratching my head.

I know, but that's an anecdotal observation rather than a controlled experiment. Who knows what caused it, as there are many factors that are not controlled. Dak27 on the other hand reported similar oil-pressure behavior on his semi for various CJ-4 vs. CK-4 oils, and he noticed one particular oil being seemingly different, but again we have the problem of uncontrolled variables in anecdotal observations.

Perhaps other members have some explanation of what you observed. However, there is nothing in CJ-4 vs. CK-4 that would result in what you saw.

You said your cooling temperature reached 205 °F (96 °C). This is pretty high. Did you experience this frequently before? If you didn't, I would suggest you have your cooling system checked. It could also be the combination of a heavy load, a steep grade, a high speed, and a hot day at the same time.

 

[LubricatusObsess]

Gokhan,
Is the BO DV150 = HTFS viscosity calculator you developed meant as a relative comparison tool between various formulations only? i.e. - not for absolute pass/fail criteria of a formulation's suitability?

Trying to catch up to full comprehend where state of the art is.

Thx!

 

[userfriendly]

I'm quite sure without looking that our track mobiles have the same engine.

www.trackmobile.com

 

[Gokhan]

Originally Posted by LubricatusObsess
Gokhan,
Is the BO DV150 = HTFS viscosity calculator you developed meant as a relative comparison tool between various formulations only? i.e. - not for absolute pass/fail criteria of a formulation's suitability?

Trying to catch up to full comprehend where state of the art is.

Thx!

SAE J300 specifies only KV40, KV100, and HTHS, in addition to the cold specs MRV and CCS.

SAE J300 specifies neither the temporary shear/VII content (except as zero (monograde) or nonzero (multigrade)) nor the HTFS. These are additional properties I have estimated with my calculator to help with the oil selection.

Nevertheless, the importance of the base-oil viscosity HTFS has been emphasized in the industry recently in relation to the engine wear.