How do you know how much VII's in motor oil?

[NH73]

How is one to know how much Viscosity Index Improver is in motor oil? I have also heard that synthetic oil has no or less amounts of VII's than there conventional counterparts. Is that true? Would a 5w30 synthetic have as much or less than a 10w30 conventional motor oil.

 

[CT8]

Basically the higher the viscosity index the higher the amount of viscosity improvers. But it is more complicated these days with the many base oils and blends. I am sure more enlightened people will post.

 

[Tom NJ]

VI Improvers vary in their thickening efficiency, and base oil mixtures vary in their VI, so unless you know exactly which VI Improver and which base oils are used, you cannot know the percentage of VI Improver. There are no reliable rules of thumb, and even laboratory analytical methods are very difficult. All else being equal, if a synthetic base oil blend starts with a higher VI than a mineral oil (they don't necessarily have to) it should require less VI Improver to achieve its target viscosity grade.

The quantity of VI Improver used is not important, but the quality may be, such as its shear stability, oxidative stability, and dispersancy characteristics. The more shear stable VI Improvers are usually less efficient and require a higher dosage.

Trying to predict an oil's performance from its VOA and physical properties is an exercise in futility. Look for the certifications and approvals relevant to your application.

Tom NJ

 

[NH73]

Please enlighten me more someone. What I read according to motor oil university, that synthetic do not need VII's to get a multi-viscosity label. Yet, comparing Quaker State Advance with QS Ultimate, the Ultimate has a higher viscosity index number. I was always told the higher amount of VII's the worse for you it is, as far as shearing goes.

 

[Shannow]

Only way that the casual observer can even remotely come up with the answer is as per A Harman's approach here.

"straight weights" are Newtonian, and their viscosity doesn't change with the rate of shear. Multigrades that have VII have two viscosities, the low shear, and the HTHS, the HTHS being lower than it should otherwise be, which is reflective of the polymers shearing.

A Harman's technique compares the calculated "KV150" with the HTHS, and gives them a percentage comparison.

Take the darling of the board.
TGMO, KV40 36.1, KV100 8.5, density 0.851...HTHS is quoted as being 2.6.
Gives a "stability" of 84.4

Compare it to Citgo 20W20
KV40 64.7, KV100 9.0, density 0.878, HTHS 2.9
Gives a "stability" of 97.5, which it should as it's a straight weight.

For a given grade, density and VI will give you a feel for where they get their KV values from, basestock or VII.

 

[CT8]

Originally Posted By: NH73
Please enlighten me more someone. What I read according to motor oil university, that synthetic do not need VII's to get a multi-viscosity label. Yet, comparing Quaker State Advance with QS Ultimate, the Ultimate has a higher viscosity index number. I was always told the higher amount of VII's the worse for you it is, as far as shearing goes.
Yeah but motor oil university is potentially more opinion than fact. Not wanting to raise the ire of the poster.

 

[Shannow]

The University implication that synthetics don't use VII is just plain wrong, as is the "10W30 is a 10W, VIIed to a 20, and can shear back to 10W)

It is possible to get multigrade performance from synthetic basestock, e.g. Amsoil SAE30/10W30, but you can bet that nearly every multigrade on the shelves has at least SOME VII.

It's not a bad thing...especially since they include HTHS minimums in the J300 specs these days (well for ages)...I just pick my lubricants in the mid-high VI, I have no reason to chase the 200s, as I think that they are going too far for a reasonable application.

e.g. the Castrol Magnatec Fuel Saver in my L67 Caprice has a VI of "only" 158, HTHS of 3.2, and comes in at 91.5 in A_Harman's calcultions.

 

[dparm]

Originally Posted By: NH73
How is one to know how much Viscosity Index Improver is in motor oil? I have also heard that synthetic oil has no or less amounts of VII's than there conventional counterparts. Is that true? Would a 5w30 synthetic have as much or less than a 10w30 conventional motor oil.


You can roughly infer it by the listed viscosity index, but that's become more difficult with these next-gen basestocks like ExxonMobil's Visom and Shell GTL and XHVI.

It's not a huge area for concern, as others have mentioned. The overall formula is what matters. VIIs are not cheap so a blender isn't going to use a ton of them if they don't provide a measurable benefit.

 

[NH73]

Thanks everyone. Say if I am putting motor oil in a Kawasaki FR730V engine(an air-cooled engine with an oil filter typically stuck on outdoor power equipment), is there a number like the VI and the HTHS, I should go above or below? I know this probably should be on the OPE part, but I started this trying learn what these VII's are and trying to keep things the same.