Synthetic Oils With Lowest VII's ?

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I always thought higher VI number is better since it is thicker and maintains it's viscosity with less shearing. I read that somewhere on this website. I guess I am wrong.

Next, why are some choosing 5w-30 when an engine requires 5w20? Isn't it because 5w-30 is thicker is better?
 
Originally Posted by painfx
I always thought higher VI number is better since it is thicker and maintains it's viscosity with less shearing. I read that somewhere on this website. I guess I am wrong.

Next, why are some choosing 5w-30 when an engine requires 5w20? Isn't it because 5w-30 is thicker is better?

VI refers to resistance to thinning over a broad(er) range of temps and not necessarily thicker. An SAE30 will provide a thicker oil film between moving parts than say a SAE20, thus the thinner you go the greater the chances of contact between moving parts and careful selection of performance additives and BO becomes increasingly important the thinner things get.

I'm the wrong person to be answering this because I think this "fear" of VII's is waaaay over exaggerated. While quality of VM's do vary, VM's are way better now than they've ever been. Look at the 100c viscosity on recent UOA's, 5w30's and Xw40's are staying "in grade" over longer drain intervals than ever before. If all this turbo coking and shearing was happening, as has been suggested in this thread, where's the graveyard of engines?..yet even with multi grade oils using VM's, engines are lasting longer than ever. Used to be 100k was considered high mileage...now it's 150k or more. Some of that's a testament to better machining and engineering but the quality of modern lubricants and additives also plays a part. I'm pretty sure if you could prove these VM's are causing issues/failures in engine's you could bring a warranty case against one of the many lubricants mfgs that guarantee their oils won't be the death of your engine. ... Truth is, only the BITOG community will fret over the treat rate of VM's while the greater population of motorists just keeps motoring on using bulk lubricant from your friendly neighborhood qwikie lube.
 
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Originally Posted by Mad_Hatter
Side Note: Does this mean RIP 0w40; you were fun while it lasted?🤔...‚

Not necessarily. See my table posted above. M1 0W-40 has the same amount of VII as M1 5W-30, and yet it has a thicker base oil than M1 5W-30. This is because M1 0W-40 uses higher-quality base stocks than M1 5W-30.
 
few experts & industry experts here have said that VIIs are not as bad as people think ... Sounds like they are also expensive so it's used as needed.
 
Originally Posted by Mad_Hatter
VI refers to resistance to thinning over a broad(er) range of temps and not necessarily thicker.

The real trick of the VII is that it thickens the oil without substantially altering the cold-cranking (CCS) viscosity. Yes, it will alter it, but since VIIs temporarily shear during the cold-cranking test, it won't be dramatic. The cold-pumping viscosity MRV will change more with the VII content though, as it's a low-shear test.

So, what I'm trying to say is that having a higher-VI oil won't help you when the temperatures get extremely high or extremely low. Performance at extreme temperatures are determined by the HTHS and CCS/MRV, not the VI. In fact, as I explained earlier, higher-VI oils will increase wear because the oil will have a lower HTHS100 (as opposed to HTHS150), because of the high VI ("resistance to thickening" as you called it -- 100 C is closer to typical oil temperatures than 150 C), and it also will exhibit more temporary shear in extreme conditions such as wide-open throttle because of the higher VII content.

Higher-VI oils will have higher fuel economy though, as HTHS100 will be lower, and HTHS100 and HTHS150 will both be lower in more operating conditions when shear rates increase beyond the 1,000,000 per second where they are reported, as higher VII content will exhibit more temporary shear.

In summary: For wear and deposit control, you want a low VI and low VII content, and for fuel economy, you want a high VI and high VII content.
 
Originally Posted by Gokhan
Originally Posted by SR5
Originally Posted by Snagglefoot
I got the rhythm. Mobil 1. 5W30 first. Same issue on the KV100. 5W30 has a higher viscosity than 10W30. WTH. I don't know if I would seek out a lower VII if it meant going with a lower KV100 viscosity.
M1 5W30
KV100 = 11.0 cSt
HTHS = 3.1 cP
(HTHS / KV100) = 0.282

M1 10W30
KV100 = 10.1 cSt
HTHS = 3.0 cP
(HTHS / KV100) = 0.297

So the KV100 and HTHS in the M1 5W30 is being boosted by polymer VII, which will shear and reduce both numbers in use, and it will leave more deposits.

The 10W30 has less VII, and so will shear less, keep it's KV100 and HTHS closer to it's original values, and leave less deposits.

Yep, exactly.

VI = 172 vs. 146 for M1 5W-30 vs. M1 10W-30, respectively, also showing the former has a lot more VII (7.8% vs. 4.4% (relative content), respectively, according to my estimates).



Here is another one I like. It's the Australian version of Castrol Edge 10W30, which is different from the North American version

Edge 10W-30 (API SN/CF, ACEA A5/B5, ILSAC GF-5)
Vis 40C = 66.2
Vis 100C = 10.47
Pour Point = -36C
VI = 146
HTHS = 3.2 cP

(HTHS / KV100) = 0.306
 
Originally Posted by SR5
(HTHS / KV100) = 0.306

As a note, I use

VII content ~ [ 1 - ( HTHS150 / DV150 ) ] / 2 = { 1 - [ HTHS150 / ( KV150 * density150 ) ] } / 2.

Incidentally A_Harman index = HTHS150 / DV150;

so, VII content ~ ( 1 - A_Harman index ) / 2.

A_Harman introduced his index with the goal in mind of estimating the VII content long before I expanded the calculation to estimate the base-oil viscosity.

We can introduce

SR5 index = HTHS150 / KV100.

While it's not as accurate as the A_Harman index, it's a quick way of estimating the VII content without calculating KV150 (through Widman operational-viscosity calculator), density150 (by simple scaling), and DV150. Therefore, it's useful for quick comparison of oils for their VII content.
 
Yeah, I just use it as a quick comparison tool, using data that is (should) be in the PDS.

I wouldn't go so far as to call it a index or calculator.

But it's quick and 0.3 is a nice & simple line in the sand.

Noack volatility is a good comparison tool too, the lower the better.

But you know all that, I'm just chatting for the casual reader.
 
*Gokhan : How would Castrol EDGE 5W30 and Castrol Magnatec 5W30 (two more popular synthetics) fair in % VII ?
Originally Posted by Gokhan
>> For similar oils higher KV100 means higher VII content. span>

Moreover, for oils with a similar KV100, higher HTHS means lower VII content.

Therefore, for a low VII content, you want a low KV100 and a high HTHS.


For example a 5W-20 will have less VII than a 5W-30 and its KV100 will be less as a result.

The way it technically works is that a typical VII multiplies KV40 and KV100 of a base oil by approximately the same number (although some multiply KV40 by a larger number and some KV100 by a larger number). Effectively this thickens the oil while maintaining the cold-flow properties and raises the viscosity index. This is what VIIs do: thicken the oil by maintaining the cold-flow properties. As some mistakenly believe, most VIIs do not thicken the oil more when the temperature gets higher.

You can easily tell from the KV100 numbers that Valvoline Advanced Synthetic 5W-30 has less VII than Mobil 1 5W-30.

These are the estimated relative VII contents from the table I posted at top of this thread:

Valvoline Advanced Synthetic 5W-30: 1.7% VII
Pennzoil Platinum 5W-30: 3.8% VII
Quaker State Ultimate Durability 5W-30: 6.0% VII
Mobil 1 5W-30: 7.8% VII

VAS and PP both have low KV100, which results in a low VII content. In addition VAS has a higher HTHS than PP, which results in even a lower VII content for VAS.

Base-oil viscosity and VII content estimates
 
Originally Posted by Gokhan
In summary: For wear and deposit control, you want a low VI and low VII content straight grade SAE30 and for fuel economy, you want a high VI and high VII content straight grade SAE20.

There, fixed it for you...
coffee2.gif
(ppl in cold climes, like myself, are SOL..or need to "suck it up" and use a multi grade w/VM's)
 
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Originally Posted by Mad_Hatter
Originally Posted by Gokhan
In summary: For wear and deposit control, you want a low VI and low VII content straight grade SAE30 and for fuel economy, you want a high VI and high VII content straight grade SAE20.

There, fixed it for you...
coffee2.gif
(ppl in cold climes, like myself, are SOL..or need to "suck it up" and use a multi grade w/VM's)

I hear you Mad_Hatter, and so does this graph from a SAE paper


[Linked Image]
 
Originally Posted by Triple_Se7en
Char....I think you meant to say....
It's always been my understanding that if you want e.g. a 5W30 with less VII's (in a specific brand name), then use it's 10W30 offering.

Maybe I'm wrong and misunderstood your intent.


Yes, thank you my friend!
smile.gif
 
*Pending Gokhan comments on Castrol EDGE 5W30 and Magnatec 5W30 - it looks like VAS 5W30 (on roll back at WM for $21) and PP 5W30 are hard to go wrong with in a GDI / TGDI engine .
 
I guess it was premature to declare 10w30 'obsolete'....If I had a turbo with DI which spec'd 5w30 I'd probably be running 10w30 in summer....maybe all year round in Fla. or Ca. The jugs of PP 10w30 that AA cleared in 2018 had the blue thingy on the label which claimed to be formulated to prevent LSPI.
 
Judging by the image posted by "Pat in Speedway" a few above, I am guessing one would have no issues running Amsoil's ATM Signature Series 10w30 - in the North East/Eastern Canada as a year round fill, in lieu of a spec'd 5w30.
 
Originally Posted by ofelas
Judging by the image posted by "Pat in Speedway" a few above, I am guessing one would have no issues running Amsoil's ATM Signature Series 10w30 - in the North East/Eastern Canada as a year round fill, in lieu of a spec'd 5w30.

Depending on the starting temperature. Here in Northern Wisconsin where it can and does get down to -30F, no.
 
I recall Amsoil ATM = no VII

Your classic PAO real synthetic oil.

I would add some magnatec to it to make it better

I have a French PAO in the VW.

PAO aint all that alone, it got "issues".

A Bit of Magnatec made it stunning

What magic elixir is in that moss-green bottle ? !
 
My 42 year experience using M1 oils has been great. I have never had an engine develop varnish, sludge, or evidence of ring coking.
 
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