Visc. @ 100°C after shearing: 10W30 HM vs 0W40

[RPMster]

The general consensus over the years has been that oils with wider cold/hot viscosity spreads (e.g. 0W40) typically show a higher % of shear than oils with a narrower viscosity spread (e.g. 10W30). Let's compare Mobil 1 0W40 and Mobil 1 High Mileage 10w30. Both start with a similar hot viscosity rating, with the 0W40 being a little bit thicker (12.0 vs 12.9).

Now, let's set up a "virtual" comparison test:

- both oils are used in identical vehicles, under identical conditions
- drained and sampled at 7,000 miles
- the two vehicles have turbo DI engines and are driven hard

For the sake of simplicity, we'll say that both engines consumed 1 qt of oil during our 7,000 "virtual" test, and that there are zero variables involved which may have otherwise impacted the results.

So after both samples are analyzed, what would you expect? After shearing, would the Mobil 1 High Mileage 10w30 oil end up with a higher viscosity at 100°C compared to the Mobil 1 0W40 (such as 11.5 vs 10.0)? Or, would both oils likely be very close to the same viscosity (such as 10.5 vs 10.0)?

It would also be great to hear experiences from anyone who has done a similar comparison.

 

[FCD]

Mobil 1 0W40 is on the light end of 40 grades and while it is a great oil it would have probably sheared down to just about the same viscosity as the new 10W30 HM.

 

[RPMster]

Actually, from what I've gathered, it is not uncommon for Mobil 1 0W40 to shear a lot more than that (down into the 10 range). As an added note to my original post, I suspect we would see a similar pattern between a 5W30 and a 5W20, with the 30 shearing a lot more than the 20, over thousands of miles in use.

 

[69GTX]

A nearly 1 pt "head start" is pretty formidable. I think the 0w-40 wins out in the end, though maybe not by much.

 

[SR5]

Both the Mobil 1 oils are A3 rated, which means they need to pass a 30 cycle shear stability test, and "stay in grade".

Still my money is on the 10W30 HM, but I really don't know, just a guess.

 

[RPMster]

Originally Posted By: 69GTX
A nearly 1 pt "head start" is pretty formidable. I think the 0w-40 wins out in the end, though maybe not by much.


Correct, but then the question is this: if the 0W40 shears down into the 10 range, will the 10W30 HM also shear down into that range? Or, does the 10W30 HM typically only get down into the 11 range?

Remember, as stated in my original post, the difference between "0" and "40" (0W40) is considerably larger than the difference between "10" and "30" (10W30), so this logically would affect the shear rate between the two significantly.

As to whether or not this is actually the case in real world results, I was wondering if anyone had any applicable first- or second-hand experience with this.

 

[RPMster]

Originally Posted By: SR5
Both the Mobil 1 oils are A3 rated, which means they need to pass a 30 cycle shear stability test, and "stay in grade".

Still my money is on the 10W30 HM, but I really don't know, just a guess.


I suspect the same. I wonder how the 30 cycle test you mentioned would compare to that theoretical 7,000 miles of use in my "virtual test" ...

 

[slybunda]

Ow tends to shear down more than 5w which shears more than 10w oils.

 

[TiredTrucker]

And NOACK rate generally is higher to lower between 0wXX, 5wXX, and 10wXX oils.

 

[Ducked]

Dunno. If I'm reading this right viscosity for quite a lot of multi's increases after shearing.

http://www.api.org/~/media/Files/Certification/Engine-Oil-Diesel/Publications/4-Trends-in-Shear-Stability-of-Automotive-Engine-Oils.pdf

Results presented are mostly for 5w30 oils (not one of your "mind experimemt" oils), and its unclear how or if the test conditions are relevant to your 7000 miles, but its apparently a growing trend.

Of one of the source papers (not accessible directly from a quick look) they say:-

"VM chemistry does play a role in the viscosity increase phenomenon, although the authors were not sure why."

(Low-Temperature Rheology of Engine Lubricants Subjected to Mechanical Shear: Viscosity Modifier Effects, M. Covitch, J. Weiss, I. Kreutzer;Lubrication Science 11-4, August 1999).

Straight-weight oil keeps looking better and better.

 

[69GTX]

"Let's compare Mobil 1 0W40 and Mobil 1 10W30 HM."

In that comparison the HM version is getting close to the 40 grade specs. So what if we made this comparison a little more realistic and compared the Mobil 1 0w40 (12.9 vis) to the regular Mobil 1 10w30 (10.1 vis). A lot depends which one you choose. In fact the Mobil 1 High Mileage variants are closer to 40 grades than they are to 30 grades.

 

[Jetronic]

Originally Posted By: Ducked
Dunno. If I'm reading this right viscosity for quite a lot of multi's increases after shearing.

http://www.api.org/~/media/Files/Certification/Engine-Oil-Diesel/Publications/4-Trends-in-Shear-Stability-of-Automotive-Engine-Oils.pdf

Results presented are mostly for 5w30 oils (not one of your "mind experimemt" oils), and its unclear how or if the test conditions are relevant to your 7000 miles, but its apparently a growing trend.

Of one of the source papers (not accessible directly from a quick look) they say:-

"VM chemistry does play a role in the viscosity increase phenomenon, although the authors were not sure why."

(Low-Temperature Rheology of Engine Lubricants Subjected to Mechanical Shear: Viscosity Modifier Effects, M. Covitch, J. Weiss, I. Kreutzer;Lubrication Science 11-4, August 1999).

Straight-weight oil keeps looking better and better.



They're talking about HD diesels and soot accumulation.

Quote:
In the field test, the KV fell early and increased later for all oils except those formulated with VM RI3. The initial viscosity loss is related to mechanical shearing of the VM and subsequent increase is due to accumulation of suspended contaminants/insolubles. VM chemistry does play a role in the viscosity increase phenomenon, although the authors were not sure why.

 

[userfriendly]

I'll dig back 12 years in the used oil analysis threads and bump a 0W40 Duron in an 04 C240 Benz.
For the test I ran it 30% past the OLM only to find it full of gasoline from blown spark plugs.
Two plugs per cylinder, I couldn't tell the difference in power or fuel economy.

 

[Ducked]

Originally Posted By: Jetronic
Originally Posted By: Ducked
Dunno. If I'm reading this right viscosity for quite a lot of multi's increases after shearing.

http://www.api.org/~/media/Files/Certification/Engine-Oil-Diesel/Publications/4-Trends-in-Shear-Stability-of-Automotive-Engine-Oils.pdf

Results presented are mostly for 5w30 oils (not one of your "mind experimemt" oils), and its unclear how or if the test conditions are relevant to your 7000 miles, but its apparently a growing trend.

Of one of the source papers (not accessible directly from a quick look) they say:-

"VM chemistry does play a role in the viscosity increase phenomenon, although the authors were not sure why."

(Low-Temperature Rheology of Engine Lubricants Subjected to Mechanical Shear: Viscosity Modifier Effects, M. Covitch, J. Weiss, I. Kreutzer;Lubrication Science 11-4, August 1999).

Straight-weight oil keeps looking better and better.



They're talking about HD diesels and soot accumulation.



Well they might be, I suppose. Can't say otherwise since I havn't seen the full paper, but neither the presentation nor the abstract of the paper quoted say that.

The former refers to a taxi-fleet, the latter to "a passenger car fleet test". I suppose I was assuming they'd be US taxi's and using petrol (er..gasoline), and I'd expect if they were talking about soot they'd say so.

I know viscosity starts to increase with old/degraded oil due to polymerisation of oxidation products, and that isn't a novelty, but the presentation gives me the definite impression that they are talking about something new involving VI's, because that is what they say, though without much detail.

"This behavior of viscosity increase with shear was observed primarily on 5w30 oils, and primarily those purchased in Europe.

This trend has been growing over the last several years and is spreading to the other regions of the world."

 

[Leonardo629]

My Mobil 1 0W40 VOA showed virtually no viscosity loss in 4000mi of use.

12.61 cSt vs. 12.9 cSt published by Mobil

 

[BrocLuno]

Originally Posted By: Ducked
Dunno. If I'm reading this right viscosity for quite a lot of multi's increases after shearing.

http://www.api.org/~/media/Files/Certification/Engine-Oil-Diesel/Publications/4-Trends-in-Shear-Stability-of-Automotive-Engine-Oils.pdf

Results presented are mostly for 5w30 oils (not one of your "mind experimemt" oils), and its unclear how or if the test conditions are relevant to your 7000 miles, but its apparently a growing trend.

Of one of the source papers (not accessible directly from a quick look) they say:-

"VM chemistry does play a role in the viscosity increase phenomenon, although the authors were not sure why."

(Low-Temperature Rheology of Engine Lubricants Subjected to Mechanical Shear: Viscosity Modifier Effects, M. Covitch, J. Weiss, I. Kreutzer;Lubrication Science 11-4, August 1999).

Straight-weight oil keeps looking better and better.



Agreed

This all has to do with the VII and VM chemistry involved. There are a whole range of viscosity additives available to refiners. Which one are used are hard to tell unless they voluntarily tell us, and most won't. So run this test again between say M1 and Rotella T6 and see how it goes. Much different answer ...

 

[KCJeep]

You need to be looking at HTHS not kv@100 IMO. But the HTHS of those two oils is very close as well, the 10w30 is 3.5 and the 0w40 around 3.6 or 3.7 IIRC. Both are very good oils and operational viscosity wise it's gonna be a wash IMO. Pick the one that better suits your needs. The 0w40 probably has a higher percentage of the best base stocks.

 

[69GTX]

Originally Posted By: Leonardo629
My Mobil 1 0W40 VOA showed virtually no viscosity loss in 4000mi of use.

12.61 cSt vs. 12.9 cSt published by Mobil



Was that on the latest FS version (available since Feb 2016) or was it possibly the older version (pre-FS) where viscosity was 13.6-13.9?

 

[carbon12]

I have not used Mobil 1 0w40, but in my Cruze 1.4 turbo Mobil 1 High Mileage 5w30 had a KV100 of 11.1 cSt after 6k miles (90% highway). It starts out about 11.5 I think so I would consider that rather stable and would expect the HM 10w30 to be even more stable.

Do a used oil analysis on each and let us know.

 

[carbon12]

Also would like to mention that I replaced valve cover yesterday on the Cruze. Been using Mobil 1 High Mileage for the past 50k. Quaker State Ultimate Durability before that. 173 k on the odo. No sludge. Everything looked really clean.