I have, in the past suggested that some of the chasing VI that some of the OEMs are chasing was silly, and needlessly bolstering KVs for a given HTHS.
A while back we were using A Harman's shear stability index, which got slagged because people didn't get what it was trying to show.
It obtained a KV150, through a viscosity calculator, then converted it into Cp, the dynamic viscosity, and what the HTHS is measured in. If the oil was Newtonian, then the Low Shear and High Shear results should be the same...the ratio of HTHS to calculated dynamic viscosity is an indicator of the temporary shear that exists in the formulation.
It's not, as was the accusation, being used as an indicator of the quality, shear performance in service and the others, it was simply the non Newtonian effects of that formulation.
I'm using the following tools...
http://www.assalub.com/aktuellt.asp?lang=eng (they have an android viscosity/temperature calculator); and
http://planetcalc.com/2834/ (it's a density calculator, gets away from the corrector in A Harman's formula, ad makes the KV150/Cp@150 more intuitive, which was the problem with the recent discussions on the issue.
No particular rhyme nor reason for the oils I'll do some numbers on here, other than I need KV40, KV100, HTHS, MRV, density and CCS.
Citgo Citguard 20W20 - chosen as it's Newtonian (straight grade), with a W performance.
Calcd Cp150 2.86, HTHS 2.9, gives an SSI of 1.01, should be 1, as it's a Newtonian oil.
M1 V-Twin (20W50)
Calcd Cp150 6.26, HTHS 6.08, gives an SSI of 0.97, close as to Newtonian.
Will
move to QSUD, admittedly an aged PDS, but it's got the needed information across a bunch of grades.
0W20, Calced Cp150 2.85, HTHS 2.6, SSI 0.91
5W30, Calced Cp150 3.46, HTHS 3.0, SSI 0.87
5W50, Calced Cp150 5.80, HTHS 4.1, SSI 0.71
10W30, Calced Cp150 3.47, HTHS 3.1, SSI 0.89.
And for Giggles, and because I'm liking what I see in this oil, Ranevol 0W16.
0W16, Calced Cp150 2.45, HTHT 2.4, SSI 0.98
Now, back to the point that I'm getting to...I've wanted for a while to understand what the "high shear viscosity index is versus the KV viscosity index...still haven't found anything.
However, the two cold end parameters that define the "W" rating, the CCS and the MRV are a high shear (10^5) and extremely low shear rate respectively.
The CCS is supposed to simulate the high shear rates in a bearing/cylinder wall interface, while the MRV is supposed to simulate how the oil will "fall" to the pick-up, and be sucked up the inlet pipe.
Here's the figures...
Citgo 20W20, CCS 3,050 at -15C, MRV 7,100 at -20C.
M1 VTwin, CCS 7,500Cp at -15C, MRV 14,000 at -20C.
QSUD
0W20, CCS 4,840 at -35C, MRV 17,500 at -40C
5W30, CCS 3,980 at -30C, MRV 12,800 at -35C
5W50, CCS 4,600 at -30C, MRV 23,300 at -35C
10W30, CCS 3,650 at -20C, MRV 9,400 at -30C.
Ravenol 0W16, CCS 4,400 at -35C, MRV 10,400 at -40C.
Using the "doubling rule" (not really a rule, but close), an oil's Cp will double for each 5C change that the oil experiences...so if it's 20,000Cp at -40C, it's going to be very close to 10,000Cp at -35C.
So the MRV in a Newtonian fluid should be double the CCS, as shear rate has no effect.
Looking at the 20W20, which at least should be Newtonian, the MRV/CCS is 2.3...close.
Take the M1 VTwin, another very very high SSI, and it's 1.9, again pretty close.
QSUD
0W20, 3.6, meaning that the ability to enter the pick-up is about half what it's CCS would suggest for a Newtonian).
5W30, 3.2
5W50, 5.1
10W30, 2.6
So clearly, the action of the VIIs, while contributing to a reduced HTHS for a given KV at the hot end, are increasing the resistance to flow into the pick-up t the lower end.
The Ravenol ? It's 2.4.
Note, the above is just a statement of observation, not a poke at any particular oil, VI in general, or anyone's opinions.
It's strengthened my belief that 5W50 is a silly grade, that could be replaced with a well built 40 grade.
It's got me excited with the 0W16 grades, and am looking forward to seeing more of them, and if they are built similarly...I'd take Ravenol 0W16 over any of the Japanese high VI 0W20s any day.
A while back we were using A Harman's shear stability index, which got slagged because people didn't get what it was trying to show.
It obtained a KV150, through a viscosity calculator, then converted it into Cp, the dynamic viscosity, and what the HTHS is measured in. If the oil was Newtonian, then the Low Shear and High Shear results should be the same...the ratio of HTHS to calculated dynamic viscosity is an indicator of the temporary shear that exists in the formulation.
It's not, as was the accusation, being used as an indicator of the quality, shear performance in service and the others, it was simply the non Newtonian effects of that formulation.
I'm using the following tools...
http://www.assalub.com/aktuellt.asp?lang=eng (they have an android viscosity/temperature calculator); and
http://planetcalc.com/2834/ (it's a density calculator, gets away from the corrector in A Harman's formula, ad makes the KV150/Cp@150 more intuitive, which was the problem with the recent discussions on the issue.
No particular rhyme nor reason for the oils I'll do some numbers on here, other than I need KV40, KV100, HTHS, MRV, density and CCS.
Citgo Citguard 20W20 - chosen as it's Newtonian (straight grade), with a W performance.
Calcd Cp150 2.86, HTHS 2.9, gives an SSI of 1.01, should be 1, as it's a Newtonian oil.
M1 V-Twin (20W50)
Calcd Cp150 6.26, HTHS 6.08, gives an SSI of 0.97, close as to Newtonian.
Will
move to QSUD, admittedly an aged PDS, but it's got the needed information across a bunch of grades.
0W20, Calced Cp150 2.85, HTHS 2.6, SSI 0.91
5W30, Calced Cp150 3.46, HTHS 3.0, SSI 0.87
5W50, Calced Cp150 5.80, HTHS 4.1, SSI 0.71
10W30, Calced Cp150 3.47, HTHS 3.1, SSI 0.89.
And for Giggles, and because I'm liking what I see in this oil, Ranevol 0W16.
0W16, Calced Cp150 2.45, HTHT 2.4, SSI 0.98
Now, back to the point that I'm getting to...I've wanted for a while to understand what the "high shear viscosity index is versus the KV viscosity index...still haven't found anything.
However, the two cold end parameters that define the "W" rating, the CCS and the MRV are a high shear (10^5) and extremely low shear rate respectively.
The CCS is supposed to simulate the high shear rates in a bearing/cylinder wall interface, while the MRV is supposed to simulate how the oil will "fall" to the pick-up, and be sucked up the inlet pipe.
Here's the figures...
Citgo 20W20, CCS 3,050 at -15C, MRV 7,100 at -20C.
M1 VTwin, CCS 7,500Cp at -15C, MRV 14,000 at -20C.
QSUD
0W20, CCS 4,840 at -35C, MRV 17,500 at -40C
5W30, CCS 3,980 at -30C, MRV 12,800 at -35C
5W50, CCS 4,600 at -30C, MRV 23,300 at -35C
10W30, CCS 3,650 at -20C, MRV 9,400 at -30C.
Ravenol 0W16, CCS 4,400 at -35C, MRV 10,400 at -40C.
Using the "doubling rule" (not really a rule, but close), an oil's Cp will double for each 5C change that the oil experiences...so if it's 20,000Cp at -40C, it's going to be very close to 10,000Cp at -35C.
So the MRV in a Newtonian fluid should be double the CCS, as shear rate has no effect.
Looking at the 20W20, which at least should be Newtonian, the MRV/CCS is 2.3...close.
Take the M1 VTwin, another very very high SSI, and it's 1.9, again pretty close.
QSUD
0W20, 3.6, meaning that the ability to enter the pick-up is about half what it's CCS would suggest for a Newtonian).
5W30, 3.2
5W50, 5.1
10W30, 2.6
So clearly, the action of the VIIs, while contributing to a reduced HTHS for a given KV at the hot end, are increasing the resistance to flow into the pick-up t the lower end.
The Ravenol ? It's 2.4.
Note, the above is just a statement of observation, not a poke at any particular oil, VI in general, or anyone's opinions.
It's strengthened my belief that 5W50 is a silly grade, that could be replaced with a well built 40 grade.
It's got me excited with the 0W16 grades, and am looking forward to seeing more of them, and if they are built similarly...I'd take Ravenol 0W16 over any of the Japanese high VI 0W20s any day.
