Motor oil with the highest viscosity index

[OVERKILL]

Originally Posted By: Ohle_Manezzini
Originally Posted By: Shannow
Originally Posted By: Ohle_Manezzini
Originally Posted By: CT8
High VI in a finished engine oil means higher viscosity improver amounts.


Do you really think so? Oils don't have natural Viscosity Index, some more other less?


If PAO6 has a VI of 135-140, and a finished oil is somewhere from 160-200+, then obviously:
* anything over 140 has VII
* the higher the VI, the more VII for any given basestock.


Not at all, Again. Mpao has a viscosity index of 200, without any VII.

Yeah, the one that is 156cSt.

Assuming we are talking about Mobil's mPAO, their thinnest SpectraSyn Elite mPAO is the 65, which is 65cSt @ 100C and has a VI of 179.
The other, thicker products, are the SpectraSyn Elite 150, which is 156cSt @ 100C and has a VI of 210 and the SpectraSyn Elite 300, which is 303cSt and has a VI of 241.

For any of those products to be useful they have to be significantly diluted with a lighter base that will have a much lower VI.

You could play around with the Widman Visc calc to get an idea as to what ratios we'd be looking at here. For example, if we wanted to blend an xW-20 with a 100C visc of 9cSt, making it a heavier 20 weight, we could start with some Mobil SpectraSyn 4, mixed with SpectraSyn Elite mPAO @ 72%, this gives us a 100C visc of 9.01cSt, perfect! That same ratio, using our 40C values gives us 50.13cSt. That results in a VI of 162.

Let's get even WILDER! We'll use the SpectraSyn Elite 300 with its even higher VI:, at 75% SpectraSyn 4 and 25% 300, we end up with 8.98cSt @100C, pretty good. We end up with 49.51@40C, which gives us a VI of 164.

Would be interesting to play around with the even lighter SpectraSyn 2 (1.7cSt) to see what that yields but generally oils with very high VI's are due to the presence of VII.

 

[Ohle_Manezzini]

Yes we can calc to take most of VII out, since notwithstanding that I like thicker oils, any 155 VI for warm climate like Brazil is great, neh? I start with a 15wxx anyday. Now you know how Joe Gibbs eats it all Nascar titles.

For a bike oil that's elixir.

 

[OVERKILL]

Originally Posted By: Ohle_Manezzini
Yes we can calc to take most of VII out, since notwithstanding that I like thicker oils, any 155 VI for warm climate like Brazil is great, neh? I start with a 15wxx anyday. Now you know how Joe Gibbs eats it all Nascar titles.


Yes, you can, and that's exactly what I was doing above by starting with a light PAO to mix with the mPAO to get the best "bang" out of the mPAO so to speak. Not sure as to how good the W rating would have been on the above products, but probably decent given the bases.

 

[Ohle_Manezzini]

Now we're talking. I liked you calc efforts there, pretty smart blender you are.

 

[Ohle_Manezzini]

Originally Posted By: OVERKILL
Originally Posted By: Ohle_Manezzini
Originally Posted By: Shannow

High VI in a finished engine oil means higher viscosity improver amounts.


Do you really think so? Oils don't have natural Viscosity Index, some more other less?



Would be interesting to play around with the even lighter SpectraSyn 2 (1.7cSt) to see what that yields but generally oils with very high VI's are due to the presence of VII.


Maybe you could even use a good percent of that thin 1-decene to make PCMO!

 

[zeng]

Addition of additives package into combined base oil VI of X,with my limited understanding, would have given a VI of fully formulated oil at say,X+10 or so . Could somebody comment this ?

 

[Shannow]

Originally Posted By: Ohle_Manezzini
Not at all, Again. Mpao has a viscosity index of 200, without any VII.

LOL, are there any oils that are mPao ?

Or is it used as an additive...at additive treat rates...as a Viscosity Index Improver ?

Hint...

now show me a basestock with the sorts of VI that you are quoting ?

 

[SonofJoe]

First off, super heavy mPAOs are virtually impossible to use in any significant quantity in most modern, low viscosity PCMOs. IMO, they are not a substitute for conventional polymeric VII.

Even if you could use them, I would be very wary of the high Viscosity Indexes that mPAOs appear to confer. Yes, neat mPAO calculates out to having a high VI but how much of this is 'real' and how much is this an artifact of the archaic workings of the VI equations? (which were never intended to be used on such heavy stocks). Put a few percent of mPAO in something like conventional PAO 4, remeasure the KV100 & KV40 and then recheck the VI. Does it actually go up relative to PAO 4 now that the raw inputs are in the range that the VI equations typically operate in? I dont know the answer for sure but I rather doubt it.

 

[Shannow]

Good points...

VI=0, and VI=100 were two arbitrary points based on the crudes available at the time. Not some actual, absolute measurable characteristic....throw new "out of range" numbers at them, and nonsense may well ensue.

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=3022346

 

[OVERKILL]

It would be interesting to see how the above calculations work out in real life. Generally, are the calculations not pretty close above 0C? I was under the impression they were, and below, that is where things fall apart

 

[SonofJoe]

Originally Posted By: OVERKILL
It would be interesting to see how the above calculations work out in real life. Generally, are the calculations not pretty close above 0C? I was under the impression they were, and below, that is where things fall apart

You raise what I think is an important point. Everyone talks in terms of conventional VI which takes as input the KV100 & KV40 to get a measure of the viscosity gradient with temperature. However nowerdays, it might make an awful lot more sense to define the viscosity gradient of an engine oil from either the KV100 & CCS or even KV150 and CCS.

If we did things this way, mPAO would look silly as an alternative to conventional VII polymer.

 

[MolaKule]

Quote:
Let's get even WILDER! We'll use the SpectraSyn Elite 300 with its even higher VI:, at 75% SpectraSyn 4 and 25% 300, we end up with 8.98cSt @100C, pretty good. We end up with 49.51@40C, which gives us a VI of 164.


I would not use an mPAO as a viscosity modifier. I would use it to beef up the film strength of a LV formulation.

 

[OVERKILL]

Originally Posted By: MolaKule
Quote:
Let's get even WILDER! We'll use the SpectraSyn Elite 300 with its even higher VI:, at 75% SpectraSyn 4 and 25% 300, we end up with 8.98cSt @100C, pretty good. We end up with 49.51@40C, which gives us a VI of 164.


I would not use an mPAO as a viscosity modifier. I would use it to beef up the film strength of a LV formulation.


Thanks Mola. I think that's an important point to consider. So percentage-wise, how much would you use in a formulation?

 

[Shannow]

Originally Posted By: SonofJoe

You raise what I think is an important point. Everyone talks in terms of conventional VI which takes as input the KV100 & KV40 to get a measure of the viscosity gradient with temperature. However nowerdays, it might make an awful lot more sense to define the viscosity gradient of an engine oil from either the KV100 & CCS or even KV150 and CCS.

If we did things this way, mPAO would look silly as an alternative to conventional VII polymer.


Joe, my position (more like harping on, nothing will change) is that oils should be graded xW-HTHS, rather than what's currently J300...who cares that Mobil 1 0W50 racing is a "0W-50" per J300, when the bearings know it's got the (3.8) HTHS of a 40 (and not much more than the natural 3.5 of a mono 30).

Similarly, my holy grail in hunting for papers has been a "High Shear" Viscosity Index...ie what is the VI in the high shear regime...some posit that it's parallel to the KV calculated VI, but I find that hard to believe.

High shear is where it's at in CCS, HTHS, and the places that viscosity matters in an engine...VI was developed to show how "good" your basestock was in comparison to Pennsylvania crude...we are using it beyond anything that's remotely representative of that premise.

Makes some confused experts claim that 20s are hard done by, because their KV40/KV100 ratio is better than thicker grades, but their VI is poorer...gets back to the original intent...comparing crude sources.

 

[A_Harman]

Originally Posted By: Shannow
Originally Posted By: Ohle_Manezzini
Not at all, Again. Mpao has a viscosity index of 200, without any VII.

LOL, are there any oils that are mPao ?

Or is it used as an additive...at additive treat rates...as a Viscosity Index Improver ?

Hint...

now show me a basestock with the sorts of VI that you are quoting ?


Joe Gibbs Driven advertises their use of mPAO.

 

[Shannow]

As the primary basestock ?

http://www.exxonmobilchemical.com/Chem-E...datasheets.aspx

Their least viscous is 65cst at 100C (VII only 179 at that viscosity, not the 200s that rosetta Pontual was claiming, which is the 150Cst stuff).

Gibbs 15W50 is only 17.3Cst, which would lead one to beleive that even if they DID use the lower VI 65Cst stuff, it's well less than 50%...

 

[SonofJoe]

This thing with heavy mPAO is a bit of oil formulation by sleight of hand. The essence of the 'trick' is making what's known in the trade as a 'dumbbell blend'.

At it's most basic, to make any multigrade oil, you need two base oils (one light, the other heavy) and one VII. Although it's a bit more complicated than I'm about to say, generally what you do is set the ratio of the two base oils to give you your low temperature viscocity (CCS) and then you dump VII on top until you get your desired high temperature viscosity (KV100).

Now for reasons of commercial availability, the two base oils you use are a single 'step' apart. This means for an all Group I 15W50, you would use a 150SN light base oil and a 600SN heavy base oil (for reasons of clarity ignore 350SN's are they are relatively rare and also ignore synthetics). The blend you end up with will required a VII loading of x and have a Noack of y.

However in oil formulation, there are many ways to skin a cat. There's no reason why you can't make the same oil with an ultra light 100SN base oil or an ultra heavy 2500SN base oil (called Bright Stock). This is called a dumbbell blend. In commercial operations you wouldn't do this because 100SN is a minor grade for automotive use and Bright Stock is expensive to produce and best reserved for marine applications. But in the lab you CAN make a blend that has an identical KV100 and CCS to the one made from 150SN & 600SN.

The thing is the dumbbell blend will always contain less VII and because of this, for the same KV100 it will always have a higher HTHS. This sounds great until you realise that the dumbbell blend will have a significantly higher Noack because Noack is always skewed towards the most volatile base oil in the mix.

Let's say you make a 10W30 oil with PAO 6 and PAO 8. It's on grade and has a VII loading of x. You now try and make the same blend with PAO 6 and replace the PAO 8 with heavy mPAO. You might be able to do this but because the mPAO is so heavy, you might be limited to getting in only a couple of percent which isn't enough to make a convincing case for it. So to get more in, you dump the PAO 6 for lighter PAO 4. Now you can make a decent dumbbell and lo and behold the HTHS goes up because the oil contains less VII. However now your Noack's up by 3 - 4% and how does that play against your spec?

Sneaky eh?

 

[Shannow]

great info, thanks.

 

[ndfergy]

Originally Posted By: SonofJoe
This thing with heavy mPAO is a bit of oil formulation by sleight of hand. The essence of the 'trick' is making what's known in the trade as a 'dumbbell blend'.

At it's most basic, to make any multigrade oil, you need two base oils (one light, the other heavy) and one VII. Although it's a bit more complicated than I'm about to say, generally what you do is set the ratio of the two base oils to give you your low temperature viscocity (CCS) and then you dump VII on top until you get your desired high temperature viscosity (KV100).

Now for reasons of commercial availability, the two base oils you use are a single 'step' apart. This means for an all Group I 15W50, you would use a 150SN light base oil and a 600SN heavy base oil (for reasons of clarity ignore 350SN's are they are relatively rare and also ignore synthetics). The blend you end up with will required a VII loading of x and have a Noack of y.

However in oil formulation, there are many ways to skin a cat. There's no reason why you can't make the same oil with an ultra light 100SN base oil or an ultra heavy 2500SN base oil (called Bright Stock). This is called a dumbbell blend. In commercial operations you wouldn't do this because 100SN is a minor grade for automotive use and Bright Stock is expensive to produce and best reserved for marine applications. But in the lab you CAN make a blend that has an identical KV100 and CCS to the one made from 150SN & 600SN.

The thing is the dumbbell blend will always contain less VII and because of this, for the same KV100 it will always have a higher HTHS. This sounds great until you realise that the dumbbell blend will have a significantly higher Noack because Noack is always skewed towards the most volatile base oil in the mix.

Let's say you make a 10W30 oil with PAO 6 and PAO 8. It's on grade and has a VII loading of x. You now try and make the same blend with PAO 6 and replace the PAO 8 with heavy mPAO. You might be able to do this but because the mPAO is so heavy, you might be limited to getting in only a couple of percent which isn't enough to make a convincing case for it. So to get more in, you dump the PAO 6 for lighter PAO 4. Now you can make a decent dumbbell and lo and behold the HTHS goes up because the oil contains less VII. However now your Noack's up by 3 - 4% and how does that play against your spec?

Sneaky eh?




Fascinating stuff. We know PAO's inherently have poor solubility. What other base oils are used in the mix to address this?

 

[userfriendly]

With "smart" oil pumps, pressure may not increase with thicker oil.
Maybe the highest HTHS with the lowest KV100C, the opposite of high VI is the best approach.
I found that flash point (NOACK) and HTHS are worse with high VI oils compared to mono grades for example.