Mobil AP, strange HTHS?

[dole]

1# AP 5W-30, 11.7 @100C, but HTHS only 3.0, comparing shell 5W-30, 12@100C, BUT HTHS 3.5. Huge difference, why is it so? Mobil formulate it on purpose? Isn't it true that higher HTHS is a better thing?

2# No data about viscosity @40C

Any expert shed some light?
Mobil says, AP has the best wear protection, lasts 30K KM plus.

 

[dole]

 

[FCD]

The HTHS is low on purpose, it's a ILSAC-5 and ACEA A1/B1 oil, these specs are designed for slightly better fuel economy.

 

[turboseize]

Originally Posted By: dole
1# AP 5W-30, 11.7 @100C, but HTHS only 3.0, comparing shell 5W-30, 12@100C, BUT HTHS 3.5. Huge difference, why is it so? Mobil formulate it on purpose? Isn't it true that higher HTHS is a better thing?


At least in Europe, we generally don't trust low HTHS. For good reasons, VW and Ford used to spec low-HTHS oils on some engines - with desastrous results.
The 1.0 ecoboost seems to do fine, but that engine was desgned for this lubricant. But in the past, Ford used to prescribe low-HTHS oils to Volvo engines that were clearly NOT designed to cope with them. VW first generation of long-life oils also were reduced HTHS, and after a short while they pulled back and returned to HTHS>3.5.
That is why ACEA A1/B1, A5/B5 and C2 generally have a very bad name amonst car enthusiasts here.
Nowadays you see even several european manufacturers push low viscosity oils. As CO2 targets become much harder to reach, durability becomes less important than fuel economy.
Now, that does not mean that an engine necessarily wears out faster or fails catastrophically with low HTHS oils. A friend of mine who works in the automotive industry used to run engine tests (with teardowns) and reported some of the tests with the best (i.e. least) wear were run with 0w-20 - even though oil pressures were dangerously low. Still, next to no wear. But then, there were other 0w-20 wich produced the worst wear. With thicker oils, you can separate moving parts by the oil film - with thinner oils, you NEED perfect temperature management - and you have to rely entirely on the additive package to control wear. Thick oils is physics, thin oils is witchcraft.

I won't touch a low-HTHS oil with a ten-foot pole. That is, unless I'd own an engine specifically designed for it, such as the 1.0 ecoboost. I'd never run a low-HTHS oil in an engine that was merely back-specced to do so.

 

[Gokhan]

Originally Posted By: dole
1# AP 5W-30, 11.7 @100C, but HTHS only 3.0, comparing shell 5W-30, 12@100C, BUT HTHS 3.5. Huge difference, why is it so? Mobil formulate it on purpose? Isn't it true that higher HTHS is a better thing?

2# No data about viscosity @40C

Any expert shed some light?
Mobil says, AP has the best wear protection, lasts 30K KM plus.

It's a good point there. Unfortunately the datasheet doesn't list KV40 or VI so that we could calculate the A_Harman index.

My guess is that M1 AP has very little VII and therefore very low VI. As a result, viscosity drops faster with temperature. That's probably why they chose not to list the VI and KV40. This is not necessarily a bad thing, as many people prefer less VIIs, but it's strange as you said.

It's interesting indeed!

 

[4WD]

Looks like a CAFE driven GF5 line up to me ... green label and all ... notice the cars they tested in were far from hot rides ...
You want more HTHS ? Buy a 40 or a thick 30 near the edge of range ...

 

[Gokhan]

Originally Posted By: Gokhan
Originally Posted By: dole
1# AP 5W-30, 11.7 @100C, but HTHS only 3.0, comparing shell 5W-30, 12@100C, BUT HTHS 3.5. Huge difference, why is it so? Mobil formulate it on purpose? Isn't it true that higher HTHS is a better thing?

2# No data about viscosity @40C

Any expert shed some light?
Mobil says, AP has the best wear protection, lasts 30K KM plus.

It's a good point there. Unfortunately the datasheet doesn't list KV40 or VI so that we could calculate the A_Harman index.

My guess is that M1 AP has very little VII and therefore very low VI. As a result, viscosity drops faster with temperature. That's probably why they chose not to list the VI and KV40. This is not necessarily a bad thing, as many people prefer less VIIs, but it's strange as you said.

It's interesting indeed!

One possible explanation for the unusually low viscosity index is that Mobil 1 AP contains alkylated naphthalene, which has a low viscosity index, as one of its base stocks. Has anyone smelled this oil?

This would explain the unusually low viscosity index for a 5W-30. The only other thing I can think of is a viscosity-index improver with a high temporary shear that would cause a low HTHSV without a low VI but I doubt that.

There could also be an error in the datasheet.

 

[Shannow]

Originally Posted By: Gokhan
Originally Posted By: Gokhan
Unfortunately the datasheet doesn't list KV40 or VI so that we could calculate the A_Harman index.

My guess is that M1 AP has very little VII and therefore very low VI. As a result, viscosity drops faster with temperature. That's probably why they chose not to list the VI and KV40.


One possible explanation for the unusually low viscosity index is that Mobil 1 AP contains alkylated naphthalene, which has a low viscosity index, as one of its base stocks. Has anyone smelled this oil?

This would explain the unusually low viscosity index for a 5W-30. The only other thing I can think of is a viscosity-index improver with a high temporary shear that would cause a low HTHSV without a low VI but I doubt that.

There could also be an error in the datasheet.


So you've gone in two steps from the reason that there's no KV40 and/or therefore viscosity index is because it's a poor VI.

Then used THAT MADE UP FACT to speculate that the reason that it's so low is AN.

Seriously, what are you smoking these days ?

OK, first we need evidence that there's a low viscosity index...what is it ?

 

[SonofJoe]

If I were to guess, I'd say that the Mobil 1 5W30 is based on OCP VII (which gives decent HTHS for a given KV100) whereas the Shell 5W30 is based on Hydrogenated Styrene Diene VII (which is weaker on HTHS but has other advantages).

Regarding low HTHS, I'm something of a convert to 0W20. In the last few days, I clocked up 546.2 miles on 32.0 litres (a tank full) of standard 95 RON unleaded. That's 76.8 mpg (Imperial) which to me underlines what you can do with a 2.6 cP HTHS oil.

 

[Virtus_Probi]

M1 5W30 EP has the same 3.0 HTHS...plain old M1 5W30 and the HM version are just a tad higher at 3.1.
You want some honking HTHS out of a M1 5W30, get ESP at 3.58!

 

[dole]

Wow, vivid words "Thick oils is physics, thin oils is witchcraft."

 

[ARCOgraphite]

Originally Posted By: FordCapriDriver
The HTHS is low on purpose, it's a ILSAC-5 and ACEA A1/B1 oil, these specs are designed for slightly better fuel economy.
Jeeper's FCD gave the answer (above) miles ago. Its ACEA A1 - a low HTHS oil by spec. You want improved HTHS? Look to ACEA A3,B4 or Porsche A40 spec.

And Yes, We are destroying engines here Stateside with the shoddy high VM and low HTHS oils ... At least those of us who drive like Europeans

 

[oil_film_movies]

Originally Posted By: dole
Wow, vivid words "Thick oils is physics, thin oils is witchcraft."
To me that means boundary lubrication physics and chemistry is complicated. The ability for a certain oil chemistry to set up sticky molecules and/or nano-particles on the surface to makes it work. Some oils do this better than others. Ravenol 0w16 comes to mind as one (HTHS 2.4) which really must excel to win that battle, since the hydrodynamic physics (the easy) part may not be there enough.

 

[Gokhan]

MSDS lists KV40:

KV40 = 63.33 cSt
KV100 = 11.7 cSt
Density @ 15.6 C = 0.851

PDS lists HTHSV:

HTHSV = 3.0 cP

Plugging in these numbers in online Widman International SRL calculators results in:

VI = 183
KV150 = 5.09 cSt

Using these numbers and 0.885 as the density-correction factor:

A_Harman index = 3.0 / (0.885 * 0.851 * 5.09 = 3.83) = 0.783

This is the lowest A_Harman index I've ever seen. Either the reported HTHSV is in error -- it should be more like 3.2 cP -- or Mobil 1 AP uses a very unusual, high-shearing VII. The latter could be bad because HTHSV at even higher shear rates (higher than 1,000,000 per second) could be too small to protect against wear in some applications that don't like thin oil.

 

[Shannow]

Soooo....what about that abnormally low VI which indicates the presence of AN ???

 

[Gokhan]

Originally Posted By: Shannow
Soooo....what about that abnormally low VI which indicates the presence of AN ???

I hadn't seen the MSDS and that was only one of the possibilities I had suggested, another one being a high-shearing VII. What about you harshly criticizing others' posts without providing any useful information?

 

[Gokhan]

According to the MSDSs, these are the 4 cSt PAO concentrations (for 5W-30 grades):

M1: 20 - 30%
M1 EP: 20 - 30%
M1 HM: 5 - 10%
M1 AP: 5 - 10%

So, how is it that M1 AP is claimed to be better than M1 and M1 EP while it has only a small fraction (about a third) of PAO of these oils? Could it be that M1 AP is GTL? Or is it just a cheap Group III plus marketing gimmick?

 

[1JZ_E46]

Originally Posted By: Gokhan
According to the MSDSs, these are the 4 cSt PAO concentrations (for 5W-30 grades):

M1: 20 - 30%
M1 EP: 20 - 30%
M1 HM: 5 - 10%
M1 AP: 5 - 10%

So, how is it that M1 AP is claimed to be better than M1 and M1 EP while it has only a small fraction (about a third) of PAO of these oils? Could it be that M1 AP is GTL? Or is it just a cheap Group III plus marketing gimmick?


There is a lot that doesn't show up in a SDS. For example, the more expensive mPAO base oil is not considered hazardous, and therefore not on the SDS. M1 AP could be using more mPAO and less traditional PAO. Esters also do not show up on SDS. Pour point appears to be a better indicator of base oil (GIII vs GIV/V).

 

[Gokhan]

It's true but mPAO and esters can only be used in small quantities in a base oil intended for automotive engines and mainstream use, as the former comes in only very high viscosities and the latter is highly problematic in large concentrations.

 

[1JZ_E46]

Originally Posted By: Gokhan
It's true but mPAO and esters can only be used in small quantities in a base oil intended for automotive engines and mainstream use, as the former comes in only very high viscosities and the latter is highly problematic in large concentrations.


It's hard to judge what is in a PCMO without insider knowledge. There is a lot we don't know here. I can't see XOM charging substantially more for a lesser quality product. They are probably the most reputable motor oil company. Only way to truly judge the oil is to perform a couple UOAs and compare.