How Do Viscosity Index Improvers Work?

[SonofJoe]

Originally Posted By: SR5
Originally Posted By: Shannow

Here's another one from the vault...albeit a 5W30 HDMO...


Interesting, and two very different 5W30s

SpectraSyn 6 with 12%VM, 8% Noack , KV100= 12.4 cSt and HTHS = 3.7 cP - HDEO
SpectraSyn 6 + SpectraSyn 8 with 3%VM, 6% Noack, KV100 = 10.5 cSt and HTHS = 3.2 cP - PCMO

That VII package is adding to both the KV100 and the HTHS viscosities in the HDEO.

Unless it's the few % extra Ester NP343 that is doing the heavy lifting (2% Vs 5%) or the DI (12% Vs 20%) in ( PCMO Vs HDEO)




I think I can see what's happening here and it's all being driven by the DI pack.

The HDDO 5W30 DI, at 19.9%, contains a shed load of Ashless Dispersant; far more than the PCMO DI at 12%. The extra Ashless really clobbers the CCS of the HDDO and as a result, there's no CCS head room to use PAO 8. As a consequence, the aggregate base oil KV100 drops and you need more VII to make your target KV100. As it happens, the target KV100 of the HDDO is way higher than for the PCMO because the HDDO has to make 3.5 min HTHS (it looks like they've over egged the pudding and unnecessarily gone to 3.7). As you might expect, these changes have increased the Noack of the HDDO relative to the PCMO.

To me, this comparison of 5W30 highlights just how silly modern oil formulation can be. In real-life terms, I would have absolutely no doubts that the 5W30 PCMO is way better (and cheaper!) than the 5W30 HDDO and that would hold true, even in diesel engines!

 

[SonofJoe]

Originally Posted By: zeng
Originally Posted By: SonofJoe
Going back to say the mid 90s, Euro 10W40s were even then far more constrained. Low shear 22 SSI VIIs were absolutely required to meet VWs specs while ACEA's KO30 shear spec tended to keep 10W40 KV100s around the 14.5 cst mark. Likewise Noack was mainly constrained to 13% max and this meant you couldn't physically make an all Group I 10W40; you had to use typically 20% min synthetic just to make 13% (so reducing VII loading). As ACEA specs evolved, you saw tests like the Peugeot TU5 acting as a pseudo-Noack constraint for 10W40 and upping the required level of synthetic to 30% min. The required level of Group III in 10W40 jumped again as oils were required to pass the VW TDI test to ACEA B4 such that today, Euro 10W40s are more synthetic than they are mineral.

Thanks for enlightenment.
On the basis that the above fits nicely to:


Comparing it against a Castrol Magnatec SN 10W40 without A3B4 oil ,
am I right to suggest that the Castrol Magnatec 10W40 SN without ACEA :
..has more mineral than synthetic base oil content and more VII's ;
..is of lower amount (or weaker)of DI suggesting weaker anti-oxidation; weaker detergency/dispersancy etc capability ;
..lower TBN and hence shorter OCI capability; and
..inferior to Total 10W40 A3B4 SL in every other aspect of real world performance ?

Appreciate your comparative figures between these 2 oils basing on certain assumptions.

TIA



It's difficult to give a definitive answer to this question as the Castrol 10W40 PDS doesn't tell you what you need to know to make any kind of judgement as to how much synthetic or VII it contains.

If could be that the Castrol oil is simply a Group II 10W40 which meets API SN (I would disregard the CF claim entirely as the spec is obsolete and I seriously doubt this oil would ever pass the Cat 1MPC test). It might need to contain a smidge of Group III to get the Noack below 15% max but if say, it contained a low treat DI (for just SN) and it was made with Jurong Group II stocks, I doubt if it would need any Group III. This being the case, this oil would contain a tonne of VII and I might suggest you avoid it. I might also question whether this oil meets API in name but not in spirit. I say this because if I'd have developed this oil, I'd have deffo passed the Sequence IIIG test on a 15W40 (a relatively easy pass) and 'read-across' the test to cover the 10W40 position which is permitted. However, if I ask myself, would the oil have got through the IIIG if I'd actually run it as a 10W40, to be frank, I think it would have failed badly (it's that sneakiness thing again!).

Alternatively, this could be a case of Castrol 'under-claiming' the true performance of the oil in which case everything in the garden is rosy. I guess us mere mortals will never know...

 

[SonofJoe]

Originally Posted By: Red91
So the question that comes to mind with all this information taken into account is this: are modern American 10W-40 conventional oils any less good than their 5W-30, 10W-30 and 20W-50 counterparts, or is it just that they're great but late to the party?


I'd answer your question by saying that in 2017, US 10W40s, however good, are somewhat 'irrelevant' to your needs.

Here in the UK, the historical bulk oil sequence of events (highly simplied!) was 20W50 mineral -> 15W40 mineral -> 10W40 semi-synthetic -> 5W40/5W30 full synthetic. As you can see, unlike the US, we never passed through a 10W30 mineral phase because it's tricky to make a full mineral 10W30 that meets 3.5 min HTHS. The US, with its 2.9 min HTHS spec, could always make mineral 10W30s and always placed far more emphasis of oil-related fuel economy (we just built smaller cars!). In such an environment, 10W40 for the US is an uneccessary backtrack.

 

[SR5]

Thank You Joe !!!
We would be lost without you.

 

[SR5]

Originally Posted By: SonofJoe
I had a look at the Nulon 10W40 properties. It's not what I'd call particularly well optimised. The KV100, at 15.07 cst is too high (14.3 would have been more than adequate) & the CCS, at 5270, is unnecessarily low (6700 cP would be better). This oil needs to have it's VII loading cut back and simultaneously 'heavied-up' to yield a better oil (less VII, less deposits, lower Noack, cheaper).

Given that the Nylon SDS refers to severely hydrocracked stocks (as opposed to PAO), what Nylon might want to think about is using a bit of Group II 500N as the optimising base oil. It stretches the definition of 'synthetic' but you would deffo end up with a far better oil.


Got it !! Thanks.

Closer to what you described is Penrite 10-Tenths Racing 10W40 (full PAO and Ester oil).
It's KV100 = 14.6 cSt while Cold Cranking @ -25C = 6105 cP.

It has a massive HTHS of 4.49 cP and just as high on the zinc at 1680 ppm. But it's still rated API SN and ACEA A3/B3 with a reasonable TBN of 9.8 therefore road suitable so to speak. Not everybody's cup of tea.

 

[Red91]

I appreciate your time, insight and dedication to this forum and its members. Much good info in this thread.

 

[zeng]

Appreciate your enlightening assessment SoJ.

 

[MolaKule]

Originally Posted By: SR5
Originally Posted By: Shannow

Here's another one from the vault...albeit a 5W30 HDMO...


Interesting, and two very different 5W30s

SpectraSyn 6 with 12%VM, 8% Noack , KV100= 12.4 cSt and HTHS = 3.7 cP - HDEO
SpectraSyn 6 + SpectraSyn 8 with 3%VM, 6% Noack, KV100 = 10.5 cSt and HTHS = 3.2 cP - PCMO

That VII package is adding to both the KV100 and the HTHS viscosities in the HDEO.

Unless it's the few % extra Ester NP343 that is doing the heavy lifting (2% Vs 5%) or the DI (12% Vs 20%) in ( PCMO Vs HDEO)



First of all, this simply shows how many ways a particular grade can be developed.

Secondly, one has to account for how the PI package affects or deviates from the target viscosity, then add only enough VII to reach that target.

These formulating tables are only suggestions.