Viscosity Modifiers II

Gokhan

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Originally Posted by MolaKule
Here are some interesting conclusions from an older paper on base oil viscosity and VII's: Base Oil Viscoitiy and VII by Lubrizol India - HTHS and SSI
I'm sorry to say this but this is very poor-quality research. The authors are all over the place and there is no systematic scientific approach. I would entirely ignore their conclusions. HTHS viscosity doesn't depend on the VII content? Really? One of the main uses of the VII is to adjust and tune the HTHS viscosity.
 

Gokhan

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Looking at the Lubrizol India paper more carefully, I see that they are not claiming that the HTHS viscosity does not increase with the VII content, which I thought what they were claiming and called it absurd. So, it is fine. However, looking at Table 5, I see some unusual behavior. First, the KV and HTHS viscosity columns are mislabeled and they should be switched -- actually KV (cSt) is on the left and HTHS viscosity (cP) is on the right. The rather unusual behavior I see is the collosal increase in the viscosity (colossal thickening power) -- 341.6% for OCP and 1860.7% for SIP. You don't see that in commercial oils. For example that would turn a KV100 = 6 cSt base oil into a KV100 = 118 cSt oil in the case of SIP. As a comparison SAE 60 KV100 < 26.1 cSt. Then, they see some variation of the thickening power with the base-oil viscosity as well as the VII content. I am not sure if this would be seen in practical applications of VIIs, where the thickening power is below about 140% in the extreme commercial cases -- 5W-50 and 10W-60 oils. Therefore, the nonlinear results (nonlinear in the VII content and base-oil viscosity) may be because of the unusually high VII content.
 

MolaKule

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Originally Posted by Gokhan
Originally Posted by MolaKule
Here are some interesting conclusions from an older paper on base oil viscosity and VII's: Base Oil Viscoitiy and VII by Lubrizol India - HTHS and SSI
I'm sorry to say this but this is very poor-quality research. The authors are all over the place and there is no systematic scientific approach. I would entirely ignore their conclusions. HTHS viscosity doesn't depend on the VII content? Really? One of the main uses of the VII is to adjust and tune the HTHS viscosity.
The paper does have a section in which they show the Experimental Procedure they used and the basis for their data tables. I agree editing of Figure 5's Text could have been better but again, they are stating the results dervived from their Experimental Procedure whether you agree with those results or not.
 
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Gokhan

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As I said in my previous post, they are not claiming that HTHS doesn't vary with VII content as I first thought, so, it's fine. Instead they are making some claims about the HTHS thickening rate (increase per VII content) and permanent shear. The data is probably OK and the results are somewhat interesting. As I also said in my previous post, the problem is that the thickening is so large (as large as a factor of 20) that the results don't really apply to commercial oils, in which the thickening is usually a factor of 2 or less (100% or less thickening) and virtually always under a factor of 2.5 (150% thickening). Nonlinear (in VII content and base-oil viscosity) behavior they observe, while interesting, probably doesn't appear for the range of the VII content used in commercial motor oils.
 
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Molakule, we had some issues a few years ago with ISO460 gear oils rapidly becoming 200(ish) in service. The manufacturer denied having Viscosity Modifiers in their ISO grades, pointing to the 98 VI...but within 3 months, no changes at our end on multiple pieces of equipment, the oil stopped breaking...three years later, it was back again...evidence of PIB (or similar thickeners)
I wish I knew this thread was open when it was active. It's a good subject.

Several years ago I was looking for low cost synthetic fluids or VMs (thickeners) for an ISO 680 gear oil. I formulated using a base fluid of 12% Indopol H300 (polybutene; KV100=605-655; VI=173) and bright stock (GI mineral oil; KV40=480). This would have yielded a VI of about 98-102. Long story short, I put the oil into a planetary swing transmission of an electric rope mining shovel, a high shear application. The oil began to loose viscosity within a few days and at 14 days it was down to about 525 KV40. I repeated this another time with the same result. Polybutene/PIB does not appear to be shear stable in geared system.

You can identify polybutene by infrared spectroscopy. Further, I wouldn't be surprised to see the VI drop as viscosity drops.

VMs, especially the VII type, are task specific. In other words, a VII developed for gears is stable in a geared system but not in an engine. Powersports engine oils with shared compartments are extremely damaging to many VIIs. A VII may be fine in separate compartments but when exposed to gears or a wet clutch loss viscosity immediately.
 
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I wish I knew this thread was open when it was active. It's a good subject.

Several years ago I was looking for low cost synthetic fluids or VMs (thickeners) for an ISO 680 gear oil. I formulated using a base fluid of 12% Indopol H300 (polybutene; KV100=605-655; VI=173) and bright stock (GI mineral oil; KV40=480). This would have yielded a VI of about 98-102. Long story short, I put the oil into a planetary swing transmission of an electric rope mining shovel, a high shear application. The oil began to loose viscosity within a few days and at 14 days it was down to about 525 KV40. I repeated this another time with the same result. Polybutene/PIB does not appear to be shear stable in geared system.

You can identify polybutene by infrared spectroscopy. Further, I wouldn't be surprised to see the VI drop as viscosity drops.

VMs, especially the VII type, are task specific. In other words, a VII developed for gears is stable in a geared system but not in an engine. Powersports engine oils with shared compartments are extremely damaging to many VIIs. A VII may be fine in separate compartments but when exposed to gears or a wet clutch loss viscosity immediately.
Interesting I have done exact same thing with h-300 as well as PAO 100.
Will have to maybe re think, luckly testing that unit on a routine basis the oil would fall out of vis range and should have been changed out.

All tho I have seen straight bright stock gear oils shear in some application 10% or so which I thought was odd and blamed on wrong topping off oil.
 
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