I have sinned by purchasing plastic.

A Group II 10W40 could have the same amount of polymer VII in it as a Group III 5W40, and both could have more VII than a Group IV PAO based 0W40.

Then there is shear stability, in general a more shear stable VII is less efficient and so a larger dose is needed.

The concept of delta, is good for comparing oils of the same base type, using the same VII type. All bets are off otherwise.

I like 0W oils due to their superior quality as long as they are not thin (i.e. 0W20 and lower) and good 0W30's are typically pricy ($10/qt). That leaves 0W40 and 5 qt of Euro a3/b4 for $24.xx sounds reasonable. Also iirc, these are on the lighter side of the 40 range in case someone cares about the cSt delta.

Q:
What is the impact of requiring larger dose of more shear stable vii?
Any other side effects besides I assume the price?
 
A few years ago, I asked some questions about VII here on BITOG, and was lucky to get some oil formulators answer me. I'll copy and paste below, for those interested.


Question - SR5: Just say we have three 40 weight oils from the same name brand manufacturer. The first is a top shelf, full synthetic, 0W-40, MB229.5, BMW LL-01 etc The second is a middle level, semi-synthetic, 10W-40, A3/B4 The third is a economical to purchase, mineral, 15W-40, SN What would be the differences in VII's used (type and dose rate)?
Answer - Solarent: 0W40 & 10W40 - odds are something like this would use a Styrenic Polymer but the treat rates would vary depending on the base oil choice. For example the 10W40 could have as low as 6-8% and the 0W40 as high as 18%. These VII's are generally more shear stable (5 SSI) but require more product to get the same level of thickening (polymeric efficiency). These polymers get chosen typically for shear stability, deposit control and dispersency are the main issues. Remember VII is only one part of the entire formula - so the formulator has to balance the VII needs with the rest of the DI package involved. The 15W40 would most likely contain an OCP. probably something in the 25-35 SSI range. These polymers typically have good efficiency (meaning you get the required thickening at smaller concentrations) but they don't have the same level of shear stability and some would say that higher concentrations contribute to deposits in certain engine tests. OCP's are generally the cheaper of the two, so the final price of the product may reflect that. There are lots of reasons why a formulator or oil marketer would choose to use different VII/VM packages - sometimes it's a performance requirement, sometimes its for reduced manufacturing complexity, sometimes its price. When you think about all the little details that go on to get to that final formula just right - you can probably see why formulators get annoyed when internet gurus and aftermarket companies thinks it's ok to mix in their own "special ingredients" as a way to improve on the formula - especially when there is no standardized testing involved.

Joe90_guy: Okay, from the top... Olefin Co-Polymers (OCPs) are the most widely used of the VII polymers. They are made from ethylene & propylene which are the two simplest and cheapest olefins you can get hold of. The polymers can be made long or short. The long ones are more polymerically efficient at achieving a simple viscometric balance (KV100 & CCS) but tend to shear under mechanical & thermal stress. These are the so-called high Shear Stability Index (SSI) OCPs beloved by the US. The shorter, less efficient but more shear stable, low SSI OCPs are the norm in Europe. The Shellvis VII polymers are made from stryene and butadiene. They can also contain extra hydrogen. Like OCPs, they can be made to various SSIs These olefins are more chemically complex and costly than simple ethylene and propylene. As a rough rule of thumb, Shellvis pure rubber is twice the price of pure OCP rubber. At equal SSI, Shellvis is undeniably more polymerically efficient (ie you need less rubber) than OCP at achieving a simple KV100/CCS. However when you factor in cost, OCP is far more cost efficient. This largely explains why OCP is more widely used. However life is never so simple. Today's engine oils can also be limited by Noack, HTHS, Bosch KO30 Shear and even viscometrically sensitive engine tests. Often an oil can be 'tight' on several limits simultaneously. However what limits are 'tight', and what limits 'float', will differ from viscosity grade to viscosity grade. In certain circumstances, Shellvis can match or exceed the cost performance of OCP. This tends to happen more in the top-tier engine oils but often things can be confusing. There are still a lot of formulators that subscribe to the 'it's more expensive so it must be better for top-tier' philosophy. One area where OCP's tend to trounce Shellvis VIIs is HTHS. At 100C & extreme shear (the conditions used in Bosch shear), the two VIIs are about the same. However when you ramp up to 150C (HTHS temperature), Shellvis starts to fall apart in a way that OCPs don't. I would describe myself as very much in the OCP camp. I honestly don't like Shellvis. It's not just the high cost; it's the way they encourage 'bad outcomes' (eg low Group III 10W40's) and 'cheat' certain engine tests.
 
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Members : Joe90_Guy, MolaKule, BobbyDavro and Solarent are/were all professional oil formulators, and produced some very interesting discussions in the links above.
 
Not sure about old VM discussions … ever changing and Mobil/Shell are using the Infineium star polymer
Getting the approvals 0w40 lands speaks volumes
 
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