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#4446429 - 07/01/17 04:25 AM Messing around with mixing - viscosities...
Shannow Online   content


Registered: 12/12/02
Posts: 39840
Loc: 'Stralia
You've all seen this one before that was lifeted from a Mobil blending guide...again,
not a recipe book, but some of the best information that we've got


And we "know" that the blending calculators tell you what you want to know regarding a mix, but as I've repeatedly warned, the beaviours need to be linear in response, and additive to give you the same number as a calculator.

Yep, the calculators are based on well known rules/laws for blending basestocks, but my query has always been how well they do with already formulated oils that AREN'T just simple basestocks.

A few minutes of messing should get you across the line that viscosity Modifiers, due to their nature have a lower impact in terms of viscosity modification in heavier basestocks, as the intrinsic shear stresses are higher in a higher viscosity basestock.

And typically (and especially so the 0W grade) the higher the high temperature grade, the lower the base oil viscosity, and the more VII.

Today while messing around with headlight bulbs and cabin air filters, I was pondering what mixing a monograde with a multigrade netted...whether the blending calculators made sense in those worlds, when you aren't averaging basestock viscosity and VII concentration in the traditional multigrade format, but are instead diluting with an entirely, and much thicker basestock.

So messed around with the Mobil numbers...



Points...
* the Base Oil (BOV) viscosity, particularly with the 0Ws drops with increasing high temperature grade.
* There's more (obviously) VM additive to get the higher high temperature grade with the lower BOV (shows in NOACK in the original table)
* that the simple ratio of final KV100 on calculated BOV for a given VM treat rate drops, as it should with the increasing shear stresses in the thicker base-stock.
* that within the grades (e.g. 0W, mixing say a 0W20 with a 0W40 puts the BOV AND the VM treat rate about and approximately into the 0W30 grade)...near enough for Government work anyway.


So then looked at simply adding SAE30, and SAE40 in a 1:4 ratio...look at what that does to the BOV, as it's heavier than any of them as it stands...SAE30 is 20% thicker than the calculated for the 10W60 BOV.

VM percentage reduction obviously proportional...and I can't calculate anything from it with regards to final product, but if you poke around looking at the KV ratios, and the VM rates, and the BOV, you can get a feel for what the world looks like.

Mix them 50:50 like the last lines, and ot's even more different.

My "feelings" from this (not postulating anything as facts) are that due to the non linearity in behaviour of VMs and Basestock viscosities, adding SAE30 Newtonian actually is likely to thicken almost anything, particularly ILSAC even the wide range 40s.

A 0W30/SAE30 mix could well be knocking on, or nudging in to 40 grade territory...

The 10W60 is likely going to be thinner for sure...but with half the VM treat rate, would it be more shear stable and useful ?

Just a thought experiment, and interested in the views of the guys who actually build (or built) oils for a living

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#4446433 - 07/01/17 04:42 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
userfriendly Offline


Registered: 06/03/03
Posts: 2629
Loc: LaFinDuMonde
A 50/50 blend of SAE 0W40 and SAE 30 would have a treat rate of 5.8% VII.
BOV would be 17% X #4 , 20% X #6 and 50% of the BOV of your SAE 30, likely an ISO 68 grade @ 40C.

Einstein would say something like 0W40 + 30 = 15W50

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#4446453 - 07/01/17 06:16 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
fdcg27 Offline


Registered: 09/25/09
Posts: 15687
Loc: OH
I've often wondered about the effect of the VIIs in an existing fill on a quart of straight thirty add oil.
Maybe a thinner straight grade would be better for adds, provided that one could find it.
_________________________
17 Forester 12K MSS 0W-20
12 Accord LX 86K PP 5W-20
09 Forester 95K M1HM 10W-30
01 Focus ZX3 118K PP 5W-20
96 Accord LX 104K T5 10W-30
95 318i

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#4446457 - 07/01/17 06:23 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
Donald Offline


Registered: 03/21/04
Posts: 20447
Loc: Upstate NY
Wow - you have more free time than I do.

If you mix viscosities on day one it might be what you wanted but who is to say how they will each shear over time.

I determine what I want to use based upon owners manual and get that.






Edited by Donald (07/01/17 06:23 AM)
_________________________
2015 Subaru Forester 2.5 engine/CVT
2015 Ford F250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)


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#4446461 - 07/01/17 06:32 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
userfriendly Offline


Registered: 06/03/03
Posts: 2629
Loc: LaFinDuMonde
Sorry Donald, that is the wrong answer.
We don't use owners' manuals here.
And there is no such thing as a properly formulated engine oil that we can't improve upon.
You just lost one privilege point.
Duck tape please.


Edited by userfriendly (07/01/17 06:34 AM)

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#4446464 - 07/01/17 06:40 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
Dyusik Offline


Registered: 09/26/14
Posts: 1978
Loc: US-WA
I like posts like these, thanks for keeping the bitog spirit alive.
_________________________
95 Cherokee 190K DELO 10W30,XG8
07 IS250 97K FB ?w??,FULL
04 YZF-R1 19K DELO 15w40,XG7317
99 HD XL1200S 18K 76 20w50,1515
14 RX450h 30k PP 0w20,NAPAG

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#4446468 - 07/01/17 06:43 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
Eddie Offline


Registered: 12/07/03
Posts: 9559
Loc: Florida, Cape Coral
Thank you so very much for the time you've invested Shannow. Ed Hayes
_________________________
CX5 Touring 2.5L :-)

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#4446494 - 07/01/17 07:18 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
Linctex Offline


Registered: 12/31/16
Posts: 6148
Loc: Waco, TX
Originally Posted By: Shannow

A 0W30/SAE30 mix could well be knocking on, or nudging in to 40 grade territory...


Fascinating.

At least in theory - I wonder how it works when actually put into practice?
_________________________
"The evidence demands a verdict".
(Re:VOA)"it's nearly impossible to actually know the particular additives that are in there at what concentrations."

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#4446506 - 07/01/17 07:47 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
lukejo Offline


Registered: 09/21/11
Posts: 404
Loc: IL
Interesting. So my 50:50 mix of 10w40 and SAE30 I'm currently using in commercial mowers, is likely netting me something over a 40w at high temp versus the approximate 35w I was guessing. Can't believe it hadn't dawned on me that the VM in the 10w would also affect the SAE.

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#4446546 - 07/01/17 09:31 AM Re: Messing around with mixing - viscosities... [Re: Shannow]
SonofJoe Offline


Registered: 07/23/16
Posts: 1052
Loc: Europe
When I first transferred into Crankcase, I was somewhat surprised that none of my new colleagues, even 30 year industry veterans, knew how to blend engine oil. So I asked my so-called colleagues from across the pond and they didn't know how to blend oils either (the first of many disappointments as it transpired).

The thing is, if you're used to working in fuels (as I had been doing up until that point), everyone knows how to blend. Whether you're blending gasoline, kerosene, diesel or fuel oil, there's always a methodology or a little computer program to tell you what happens to properties A,B & C if you blend components X, Y & Z in any particular ratio.

So rather than messing around with endless, time consuming and wasteful 'lab blend studies' like everyone else, I wrote my own lube oil blending program. It took a while to generate the necessary data for regression analysis but it worked. The analysis said that base oils, light or heavy, conventional or synthetic, Dispersants, Detergents, Antioxidants, ZDDP, etc all basically behave just like other hydrocarbons (ie units of -CH2-). VIIs are slightly different but as long as you de-couple their high temperature viscosities from their low temperature viscosities, they too blend all very logically.

So to comment on a couple of Shannow's points...

Yes. If for a given series of oils, you keep the W-rating the same and progressively increase the oil weight, you need a lower base oil KV100 to accommodate all that extra VII polymer and as a consequence, the Noack will rise. This rule is true for any given set of similar base oils and every VII (provided you don't compare apples to pears!).

If you blend two oils with a similar W-rating (say both have a CCS-35 of 6000 cP) but different oil weights, you will always get an oil with the same W-rating (and CCS-35 of 6000 cP) and the mixed oil KV100 will be somewhere between the KV100 of two original oils. The viscosities always blend on ln basis.

If you blend a monograde SAE 30 with a VII laden multigrade 0W30, and both oils have a KV100 of say 11.0 cst, any resultant mix will also have a KV100 of 11.0 cst but the KV40, CCS & HTHS will all change.



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#4446815 - 07/01/17 03:41 PM Re: Messing around with mixing - viscosities... [Re: Shannow]
Yah-Tah-Hey Offline


Registered: 05/26/14
Posts: 3395
Loc: Columbus,Nebraska
WHY?

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#4446833 - 07/01/17 04:02 PM Re: Messing around with mixing - viscosities... [Re: Shannow]
CT8 Offline


Registered: 10/09/14
Posts: 10925
Loc: Idaho
I have pondered those charts a few years ago and it is somewhat amazing.
_________________________
"Don't let your preconceived notions get in the way of facts."
Geoff Metcalf

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#4446849 - 07/01/17 04:14 PM Re: Messing around with mixing - viscosities... [Re: SonofJoe]
fdcg27 Offline


Registered: 09/25/09
Posts: 15687
Loc: OH
Good to know.
Am I correct in gathering that if I mix two 0W oils, I'll still have a 0W?
Also, if I blend two oils that are 30 grades at KV100, I'll still end up with a thirty grade?
_________________________
17 Forester 12K MSS 0W-20
12 Accord LX 86K PP 5W-20
09 Forester 95K M1HM 10W-30
01 Focus ZX3 118K PP 5W-20
96 Accord LX 104K T5 10W-30
95 318i

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#4446867 - 07/01/17 04:37 PM Re: Messing around with mixing - viscosities... [Re: fdcg27]
SonofJoe Offline


Registered: 07/23/16
Posts: 1052
Loc: Europe
Originally Posted By: fdcg27
Good to know.
Am I correct in gathering that if I mix two 0W oils, I'll still have a 0W?
Also, if I blend two oils that are 30 grades at KV100, I'll still end up with a thirty grade?


Yes to both questions.


Edited by SonofJoe (07/01/17 04:38 PM)

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#4446917 - 07/01/17 06:06 PM Re: Messing around with mixing - viscosities... [Re: Shannow]
PeterPolyol Offline


Registered: 03/06/16
Posts: 1345
Loc: toronto
Makes sense. 0W, 5W, 10W, 15W, 20W finished lubricants aren't known to be blended using heavy newtonian base stocks. The 'rule of thumb' given by SonofJoe also adds in quite nicely re: relationship between various xW engine oils and their base oil viscosity, regardless of KV100. Cool topic.

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