High V.I. oils, on purpose, or consequence??

[dailydriver]

NOT trying to start anything, but since this is one of the most vehement "oil war" topics on this site (next to 'thick vs. thin' LOL), I wanted to know members' takes on this, especially the knowledgeable tribologists on here.

I know that most of the above on here tend to "stay out of the fray", but some, like Solarent, are not afraid to state their cases, so their informed opinions are welcome!!

Are the very high (> 200) viscosity indexes we are seeing on some select oils actually BLENDED ON PURPOSE to get these levels, or are they merely a consequnce of the blenders trying to reach other goals for their final product??

Also, IF the V.I. number has NO BEARING WHATSOEVER on the actual performance of a motor oil (like many/most non-tribologist members on here seem to think), then WHY do ANY blenders/manufacturers even bother to get it as high as possible (IF they are actually trying to do so)?

 

[deven]

Higher the viscosity index the more expensive the oil is in most cases. So my guess would be that the blenders are trying to reach other goals. No mfg wants to out price themselves from their competitors.

 

[MolaKule]

I think it a result of using better additives and mixing in higher group base oils, and not necessarily a marketing hype campaign.

Recall that one can use also use a large amount of viscosity modifier in a Group I base oil and the oil will test out with a high VI.

 

[NateDN10]

I have no opinion, but my question is similar to the OPs.

If e.g. Mobil1 AFE 0W-20 is an excellent oil with a V.I. of 173 (not low by any means), what do you gain with a V.I. >200 as with some of the OEM-specific oils?
And as the OP asked, is the crazy-high VI the goal, or a byproduct of some other goal?

 

[IndyIan]

Aren't they just pursuing a higher HTHS number while still having a XW20 oil?
While looking through hydraulic/trans fluid specs for my tractor I was surprised to find lots of hydraulic oils with VI over 200, but these high VI oils result in very significant increases in productivity, ie more dirt moved per hour or per gallon of diesel right from cold start up to peak temperatures.

In a car engine though, I don't think VI matters as much as a motor oil doesn't spend too much time cold and as long as it doesn't thin out too much, nothing is gained with thicker oil at higher temperatures.

 

[Jeffs2006EvoIX]

This is very interesting dare I say "Trend". One would think that in an automotive application the variables are fairly consistent since most modern day engines temps are maintained to a specific temp range. Further question would be, to achieve the VI's of the "new age" products, are the temps needed to achieve this even applicable in a modern engine?

With OEM's leaning towards 10-20w oils now a days in pursuit for the best MPG's possible, I find it interesting that my VW gets the same MPG's utilizing a 40w vs my other car that utilizes a 20w. VW is a 2.0T, the latter Hyundai 1.8 in a 2011 Elantra. MPG's for both these cars is within 1 MPG of each other.

I realize that I am getting off point with the MPG aspect, but seeing that many 20w oils are reaching a 200 VI, I am just trying to see a relevancy to the "Why" unless as stated early that it is some by product of some other additive manufactures are utilizing.


Jeff

 

[Joe90_guy]

I reckon that at my peak I was 'doing' the equivalent of about one litre of engine oil per year for every car on the planet. In all my time as a formulator, I hardly ever paid any attention to Viscosity Index. The only time I used to look at VI was in completing a Candidate Data Package (CDP), which is the bit you do after all the action is over.
Does that answer your question?

 

[Pontual]

MPAO base has above 200 W/O VII.

 

[Pontual]

MPAO base has above 200 W/O VII. Wonder why I Never hear of MPAO in here... ,)

 

[dailydriver]

Originally Posted By: Joe90_guy
I reckon that at my peak I was 'doing' the equivalent of about one litre of engine oil per year for every car on the planet. In all my time as a formulator, I hardly ever paid any attention to Viscosity Index. The only time I used to look at VI was in completing a Candidate Data Package (CDP), which is the bit you do after all the action is over.
Does that answer your question?


Somewhat, but I wish I could hear this confirmed or refuted (with explanations either way) by the tribologists who themselves are actually engineering these high V.I. oils.

But I am speculating that will NEVER happen.

 

[dailydriver]

Originally Posted By: MolaKule
I think it a result of using better additives and mixing in higher group base oils, and not necessarily a marketing hype campaign.


THANK YOU Mola.

But by "better" additives (above) are you also inferring the newest asteric type viscosity index improvers, which despite all of the naysaying/denial on here, claim to be nearly shear proof (could you confirm of deny this claim as well?)??

 

[dailydriver]

Any others, Solarent maybe??

 

[Joe90_guy]

Tribologists don't engineer oils and never have. In industry speak, 'formulators' engineer oils. They assemble the oil together with the additive pack, bit by bit, and put the fully formulated oil through its paces on the engines and rigs. Most oils these days are engineered by the additive companies. There is very little true expertise left in the oil companies anymore and the OEMs are worse than useless.
TBH, I've only met one person who ever called himself a tribologist and he was a bit of a twit.
So again in answer to your question, high VII oils tend to arise out of circumstance, not because of any specific design objective.

 

[Garak]

Originally Posted By: dailydriver
Somewhat, but I wish I could hear this confirmed or refuted (with explanations either way) by the tribologists who themselves are actually engineering these high V.I. oils.

If they're formulating for an OEM that wants CAFE credits, it might be a little different than formulating for the masses.

 

[Shannow]

I've read that racing oils get their VI "by accident", and thus you end up with something that's got a 50 grade and an HTHS of 3.8...I don't beleive that for a second.

There's an HTHS target for sure, as that's the basis of most of the specs.

Clearly, VI has an impact on fuel economy, CAFE etc. so there's no surprise that in the pursuit of economy with 20 grades, they pushed that way, due to the HTHS mins and what they had to do to get an oil that was "thinner" at semi warm engine temperatures, met the HTHS minimums, and was in an SAE grade.

Look at Ravenoil 0W16, it's got a "massively" low VI compared to the "holy grail" of Japanese OEM oils...clearly on an emerging grade, they have access to the best of eveything, and only went for a lowly 170ish VII...why would they do that ?

Reading the tone of the thread, and not wanting to start anything (there's the qualifier)...nah...

 

[Joe90_guy]

I don't have access to my old tool box these days to check, but I would have thought that VI is essentially a function of the width of the viscosity grade. It will also be reflected in how tight or slack the oil has been blended. Lots of US oils have CCS's way lower than required by SAE J-300. This is usually done as a means to beat the API fuel economy tests. These slack blends will have a higher VI than the corresponding 'tight' blend.
One other thing that might be worth nothing is that in no engine oil spec I've ever worked to, be it from API, ACEA, GOSH or any OEM, have I ever seen a min or max Viscosity Index limit. Engine oil formulation is fiendishly difficult enough as is without having to worry about VI!

 

[Shannow]

Originally Posted By: Joe90_guy
One other thing that might be worth nothing is that in no engine oil spec I've ever worked to, be it from API, ACEA, GOSH or any OEM, have I ever seen a min or max Viscosity Index limit. Engine oil formulation is fiendishly difficult enough as is without having to worry about VI!


Have stated that many, many times, but good to hear it from an oil formulator.

Only time I have ever seen viscosity index used as a design parameter is in AGMA gear oil selection, where an ISO grade (KV40) is used to spec oils for operation at higher then 40C...i.e. a lower ISO grade with a higher VI is suitable, provided it's Newtonian.

 

[Shannow]

Originally Posted By: Jeffs2006EvoIX
I realize that I am getting off point with the MPG aspect, but seeing that many 20w oils are reaching a 200 VI, I am just trying to see a relevancy to the "Why" unless as stated early that it is some by product of some other additive manufactures are utilizing.


Jeff


If you are stuck with a minimum HTHS of 2.6 (until the recent J300 changes, that was the case), and the majority of usage is short trips, then have a look at the following image.

It's the heat input into the engine oil through lubricant friction alone.

So for the first minute, about 3hp is being consumed purely due to viscous friction.

If you can minimise that loss, it's going to be favourable to your test scores when it comes time to get the CAFE score.

So if you have to start at 2.6HTHS (nothing says you have to finish with it either, and CATERHAM's testing of the pre-mobil TGMO showed it dropped to 2.4HTHS literlally in miles), AND you are trying to minimise power losses in the first few minutes of operation, you end up there.

TGMO in particular (and Mobil Race 0W50) I have accused of having ridiculously high KV values for the high shear values, primarily I believe to meet J300 requirements.

The 0W16s to date are indicating that better effect can be gained by dropping the polymer treat rate and getting back to (slightly more) newtonian behaviour.

 

[Joe90_guy]

A couple of other things to toss in to this thread...

One reason why formulators don't much bother with VI is because it's something of an anachronism. Isn't it something to do with Pennsylvanian vacuum gasoil being the 100 VI reference and some other crude being zero? Maybe this was useful 100 years ago but not really today.

The other thing to say is be careful of confusing high VI base oils with high VI fully formulated engine oils. Formulating oils is a bit like squeezing a balloon. You can make an all mineral 15W50 with a gargantuan amount of VII polymer and the oil will have a certain VI. You can replace all the mineral oil with high VI base stock such a PAO but, for equal KV100/CCS, the VI oil the oil won't change much, because you will have to remove quite a lot of VII polymer.

 

[Shannow]

Originally Posted By: Joe90_guy
One reason why formulators don't much bother with VI is because it's something of an anachronism. Isn't it something to do with Pennsylvanian vacuum gasoil being the 100 VI reference and some other crude being zero? Maybe this was useful 100 years ago but not really today.


Yep, that's it...the cuts from one region were less affected by temperature and given an arbitrary 100, while others given zero...when both actually have temperature/viscosity curves...(2,2,4 trimethyl pentane, and n-heptane are similarly given octane ratings of 100 and 0 respectively)

That's why I get the giggles when there are threads that the VI calculation "penalises" certain modern grades...it's comparing them to the best of the best when the best was out of a handfull of wells 100 years ago...

It's a dimensionless number, entirely useless as a measure unless it's got an actual measured data point to attach it to (ISO grade or KV100).

a 200VI 0W20 or 200VI 0W50 do very different things, in very different applications...having a VI of 200 means nothing.