Question about VII's and HT/HS

[Steve S]

Originally Posted By: buster
I'll definitely have to do that. JAG you posted some good info before on this topic I believe. Sounds like it's a lot more complex than we think.

I am starting to find everything alot more complex than I think.

 

[Steve S]

Rheolog what??? Theologi what?? I read articles and i do not know what they mean.

 

[MolaKule]

http://en.wikipedia.org/wiki/Rheology

In oil terms, how a fluid like a lubricant flows and how it is affected by additives like polymers.

http://en.wikipedia.org/wiki/Polymer

In this 1999 patent, they are showing how various multi-grade oils can be developed using combinations of various viscosities and types of oils with polymeric thickerners or VII's.

https://bobistheoilguy.com/forums/threads/oil-rheology-iii-whats-the-lubricant.41182/

https://bobistheoilguy.com/forums/threads/additives-iv-performance-additive.41165/

 

[buster]

yeah this thread is a mess. It's to involved. meh

 

[MolaKule]

Quote:
Also, I am trying to understand how any VIIs could be a good thing, with the exception of cold-temp performance, or cost. Oils without VIIs that use expensive base stocks can provide very good cold performance and excellent high-temp performance, so I wonder how the trade-off can be a good one when you insert VIIs (unless to lower-cost base stocks).


Good question.

I think what they are trying to do in this patent is to use the lowest viscosity synthetic and Group III oils (and mixes thereof) possible for good startup flow, and then use specified amounts of newly developed Viscosity index improvers to insure the oils don't thin out excessively at high temps in order to seal the CC; a goal all formulators are attempting to meet.

And yes, lower viscosity base oils do cost less, but I don't think that is the ultimate goal of formulators. As I have stated before, one formulates for optimal conditions of performance and cost.

In other Mobil patents, Mobil showed that a mixture of low percentages of very high viscosity oils (40 cSt and greater) blended with larger percentages of lower viscosity oils (3.5 to 7 cSt) and very little or no VII's, showed very high Viscosity Indexes. The high viscosity oils (PAO's) seemed to act as polymers themselves.

 

[buster]

Thanks for explaining that.

 

[Steve S]

Originally Posted By: buster
Thanks for explaining that.
ditto.

 

[MolaKule]

From the patent disclosure of 1997, 5602086

Quote:
Concentrations of the alkylated aromatic preferably alkylated naphthalene (AN) in the PAO base stock can vary from about 1 wt % to less than about 50 wt % and preferably from about 5 to 45 wt % or 5 to about 25 wt % based on the total weight of the blend. The PAO fluids or blends in accordance with the invention may contain a carboxylic acid ester content up to but less than about 10 wt %.


Consider this. IF certain concentrations of esters contribute to hydrolytic and oxidative instability, combined with older VII's which also contribute to oxidative instability, one would want to use combinations of AN's and PAO's which have, according to this patent , better oxidative stability and hence be able to contribute to longer OCI's, since oxidative instability shortens the OCI.

And, if one uses a combination of the above base oils with improved VII's, improved oxidative stability is the result.

 

[MolaKule]

One thing to consider about patents and patent disclosures is to take them with a "grain-of-salt" and to consider the context of the patent.

You will notice that laboratory tests and computer simulations are done on these potential formulations to extrapolate performance.

Real world usage (fleet testing and daily driver experience) will determine if these formulations can prove themselves.

 

[buster]

Good point.