Why mixing PAO oils

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miro

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I know that is simple question but I cannot find the answer.

PAO base oil is know for purity /equal molecule length/.
Why the oil manufacture mix different viscosity synthetics oils?

Rules.
1. I will not judge who has the right answer. MolaKule is good contender for this job :)
2. Most likely there will be no single winner but many contributors for the final answer

Regards,
Miro
 
Last edited:
Your question was, "Why [do] the oil manufacture mix different viscosity synthetics oils?"

ANSWER: Because different engines call for different viscosities.

EXAMPLE: My sister's Mazda 3iTouring 1998cc SkyActiv calls for a 0W-20 synthetic where my Saab 9-5 SE calls for a 0W-30 or 0W-40. They're different.

Don't yell at me if I somehow misinterpreted your question. Kira
 
If I understand your question correctly,you're asking why oil companies mix different base oils instead of using pure pao (with a trace of mineral for add carrier)? Cost is my best guess. A motor oil can be made cheaper using highly refined mineral oil and sold as a synthetic vs a pao oil sold at the same price. Higher profit margin for the oil companies.
 
The oil bases or viscosities are mixed to get a desired result. Plus engine oil isn't just oil.
 
Originally Posted By: miro
I know that is simple question but I cannot find the answer.

PAO base oil is know for purity /equal molecule length/.
Why the oil manufacture mix different viscosity synthetics oils?

Rules.
1. I will not judge who has the right answer. MolaKule is good contender for this job :)
2. Most likely there will be no single winner but many contributors for the final answer

Regards,
Miro



CT8 and Kira gave you the correct answer.

Here's the way it's done:

For a full synthetic base oil, low and high viscosity Group III to Group V bases oils are mixed in specific proportions to give a specific VI and to portray certain performance characteristics such as:

1. low temperature pumpability and flow,
2. high temperature film protection
3. High temp shear resistance
4. low volatility
5. oxidation resistance

In terms of base oils, today most motor oils are mixes of Group II through Group V base oils.

Here is something I have posted many times to show by example base oil mixes and perecentages:

Quote:
A base oil for a formulated PCMO is NOT one Single viscosity of base oil as I have explained many times here.

A formulator can take a binary blend (a blend of two base viscosities), or a ternary (a blend of three base viscosities), or an n-ary (a blend of "n" viscosities where n is any number) to make a base mix oil behave any way he desires.

------------------------------
For example a 5W30

PAO 4 14%

PAO 20 56%
------------------------------
A 5W40

PAO 4 20%

PAO 6 48%

PAO 65 2%

-----------------------------
A 10W30/30

PAO 6 25%

PAO 8 44%

PAO 150 1%


A 0W20

PAO 4 54.5%

PAO 6 15%

PAO 65 0.5%



Now don't get the idea this is typical or the ONLY way to get specific viscosities.
 
Last edited:
There was a typo:

Change the 5W30 formulation to:

------------------------------
For example a 5W30

PAO 4 56%

PAO 20 14%
------------------------------
 
Originally Posted By: MolaKule
There was a typo:

Change the 5W30 formulation to:

------------------------------
For example a 5W30

PAO 4 56%

PAO 20 14%
------------------------------


and the remaining 30%?
 
Thank you very much for quick and clear answers.

The reason why I asked this question was my wrong understanding of PAO. I have used this picture
http://www.ret-monitor.com/articles/wp-c...mineral-oil.jpg

I understand the automotive application can benefits from such mixes - however they still looks for me as pure poluted PAO bases.


What about Industrial and marine applications?
Do they use pure PAO base oils?
E.G what is the base oil of Mobil SHC 600 gear oil, mixure of pure PAO ISO xxx?

http://www.mobilindustrial.com/ind/english/products_mobil-shc_mobil-shc-gear-series.aspx


What is the base oil used by mobil Mobilth SHC greases, pure PAO ISO 100,220,460,1000 or some mixture?

http://www.mobil.com/USA-English/Lubes/PDS/GLXXENGRSMOMobilith_SHC.aspx


Sorry that I ask such simple and stupid quuestions but I´ḿ not professional engineer in this branch.

Thanks,
Miro
 
Last edited:
Originally Posted By: Jetronic
Originally Posted By: MolaKule
There was a typo:

Change the 5W30 formulation to:

------------------------------
For example a 5W30

PAO 4 56%

PAO 20 14%
------------------------------


and the remaining 30%?


Additives...of various types and function.

If you calculate the KV100 of the 5W30 and 10W30 base stock blends, you'll see that they are 5.6 and 7.5cst respectively, and need VIIs and the like to bring them up to the 10 range for a 30.

e.g.

http://www.aftonchemical.com/ProductDataSheets/Lubricant Components/HiTEC-5710_PDS.pdf

http://www.aftonchemical.com/ProductDataSheets/Lubricant Components/HiTEC-7389_PDS.pdf
 
Originally Posted By: Jetronic
Originally Posted By: MolaKule
There was a typo:

Change the 5W30 formulation to:

------------------------------
For example a 5W30

PAO 4 56%

PAO 20 14%
------------------------------


and the remaining 30%?


Yep, as Shannow stated, the rest are additives.

The discussion centered around PAO base oil mixes only.
 
Quote:
I understand the automotive application can benefits from such mixes - however they still looks for me as pure poluted PAO bases.



No, there is no such thing as using pure PAO base oils OR pure ESTERS in automotive applications.


Quote:
What about Industrial and marine applications?
Do they use pure PAO base oils?


No, there is no such thing as using pure PAO base oils OR pure ESTERS in Industrial or Marine applications.
 
Originally Posted By: miro
Originally Posted By: MolaKule

No, there is no such thing as using pure PAO base oils OR pure ESTERS in Industrial or Marine applications.

Many thanks.
I have one question - just to be sure that I completely understand

Is't Mobil PAO ISO Viscosity Grade 220 gear oil a mixture of many PAO oils?

https://www.exxonmobil.com/marinelubes-e...-gear-220.aspx#


No, because PAO by itself (no matter what viscosity) would not not solve (be miscible with) any of the EP, metal deactivator, rust inhibitor etc., additives.

Mobil uses primarily AN's to do the miscibility thing.
 
Originally Posted By: miro
PAO base oil is know for purity /equal molecule length/.


Contrary to popular belief and promotions, most PAOs are not uniform, same size molecules. PAO 4 is about 90% of 1-decene trimer (C30) and about 10% of the tetramer (C40).

PAO 6, the most commonly used grade in 5W-X and 10W-X oils, contain the trimer and tetramer in almost equal amounts, plus some pentamer (C50). A molecular range of C30 to C50 is hardly uniform.

AN-5, most diesters, and many POEs have a much tighter molecular weight distribution than PAO 6.

Tom NJ
 
Originally Posted By: Tom NJ


Contrary to popular belief and promotions, most PAOs are not uniform, same size molecules. PAO 4 is about 90% of 1-decene trimer (C30) and about 10% of the tetramer (C40).

PAO 6, the most commonly used grade in 5W-X and 10W-X oils, contain the trimer and tetramer in almost equal amounts, plus some pentamer (C50). A molecular range of C30 to C50 is hardly uniform.

AN-5, most diesters, and many POEs have a much tighter molecular weight distribution than PAO 6.

Tom NJ


you can see here that they're not 100% uniform iirc

http://www.mne.psu.edu/chang/me462/handouts/synthetic bases stocks.pptx
 
But what about the visual representations of PAO being neat little spheres of constant size versus the golf/bowling ball/occasional cube representation ?
 
Originally Posted By: Shannow
But what about the visual representations of PAO being neat little spheres of constant size versus the golf/bowling ball/occasional cube representation ?


Marketing!
grin2.gif


When you consider that motor oils contain many different components including multiple base oils and additives, they have a very wide range of molecular sizes. So who cares if one of the base oils is uniform?

Tom NJ
 
We as consumers are B.Sed by the marketing. It really isn't like liquid ball bearings it is like waterskiing on a dirty lake.
 
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