Exactly how does syn oil shear?

[MoreCowbellAz]

I read a few articles, (including the oil univ series in BITOG), and I've seen that one of the differences between conventional and synthetic oil is that for example a conv 10w30 oil uses 10w base oil and adds VII to achieve 30w characteristics when hot, so when it shears that 30 w goes back towards the base 10w. Conversely, a syn 10w30 uses a 30w base and adds things the achieve the characteristics of a 10w when cold and supposedly doesn't shear away from that "hot" grade, so you don't have the shearing problem you see with conv oils.

So with that in mind, why all the talk of shearing out of grade of syn oils? I hear it all the time with the oils, particularly with the syn 5w40's and such, people claim the conv 15w40 are much more shear resistant.

How can that be, if the syn oils supposedly never shear away from that "hot" grade? I'm sure I'm misunderstanding something, so enlighten.............

 

[Mackelroy]

So with that in mind, why all the talk of shearing out of grade of syn oils?)))))))

cause they do it as quick or quicker than dino, theres not a lot of difference in that regard, they all do it.

 

[MolaKule]

All oils have VII's added to bring them to their target viscosity spread.

Since synthetic bases oils have a naturally higher VI than mineral oils, they need fewer VII's.

 

[OVERKILL]

Originally Posted By: MoreCowbellAz
I read a few articles, (including the oil univ series in BITOG), and I've seen that one of the differences between conventional and synthetic oil is that for example a conv 10w30 oil uses 10w base oil and adds VII to achieve 30w characteristics when hot, so when it shears that 30 w goes back towards the base 10w. Conversely, a syn 10w30 uses a 30w base and adds things the achieve the characteristics of a 10w when cold and supposedly doesn't shear away from that "hot" grade, so you don't have the shearing problem you see with conv oils.

So with that in mind, why all the talk of shearing out of grade of syn oils? I hear it all the time with the oils, particularly with the syn 5w40's and such, people claim the conv 15w40 are much more shear resistant.

How can that be, if the syn oils supposedly never shear away from that "hot" grade? I'm sure I'm misunderstanding something, so enlighten.............


Not quite. The 10w-xx is the cold performance target. The Xw-30 is the hot performance target. A base oil blend is selected that comes as close as possible (with the cost of doing so weighing in) to meeting both of targets and then VII's (and PPD's) are added to make up the difference. So you might have a 10w-20 that is VII'd into a 10w30 or a 15w30 that is "improved" to meet the 10W performance spec.

With synthetic base stocks it is common to be able to meet both those targets with just base stocks alone; no VII's. AMSOIL makes a 10w30 with no VII's and Redline makes a 5w30 with no VII's. The natural VI/multi visc characteristics of the base stocks allows it to meet both targets.

With regards to shear there is both temporary and permanent shear; temporary happening with the action of shearing forces in the engine that the polymers rebound from, permanent with the actual destruction of the polymer chains, eliminating their ability to expand/contract to affect viscosity.

With permanent shear (which it sounds like you are speaking of), the oil is brought back closer to the native viscosity characteristics of the base oil blend. What this lands you with will vary wildly depending on the constituents of that product. The results of permanent shear for example on a product like Mobil 1 Extended Performance 0w20, which is 70% PAO based will be markedly different than on a 0w-20 that is mostly group III based or a non-synthetic 5w-20.

Mobil's SM 0w-40 tended to shear down to a heavy 30 in service, becoming either a 0w30 or 5w30. The current iteration, which appears to leverage more PAO (around 50%) in its base oil blend is more shear resistant and generally stays in grade or very close to it.

Take a look at some of the Mobil Spectrasyn lo-vis PAO base oils to get an understanding of how good the cold performance of some of these products can be:

http://www.exxonmobilchemical.com/Chem-E...roductsservices

For example, the 10cSt product (10cSt @ 100C, 66cSt @ 40C, MRV 36,650cP @ -40C, CCS of 8,840cP @ -30C) meets the requirements for both the 10W and the SAE 30 designation as per this table:

So an oil could be blended using just that base oil with no VII's and be a 10w30. A combination of these types of base oils can be used to meet other intended viscosity spreads with very little VII being added.

 

[MoreCowbellAz]

Wow, seriously interesting info there, thanks. And yes, I forgot about temp vs permanent shearing, I was thinking about permanent.

 

[zach1900]

Originally Posted By: OVERKILL
Originally Posted By: MoreCowbellAz
I read a few articles, (including the oil univ series in BITOG), and I've seen that one of the differences between conventional and synthetic oil is that for example a conv 10w30 oil uses 10w base oil and adds VII to achieve 30w characteristics when hot, so when it shears that 30 w goes back towards the base 10w. Conversely, a syn 10w30 uses a 30w base and adds things the achieve the characteristics of a 10w when cold and supposedly doesn't shear away from that "hot" grade, so you don't have the shearing problem you see with conv oils.

So with that in mind, why all the talk of shearing out of grade of syn oils? I hear it all the time with the oils, particularly with the syn 5w40's and such, people claim the conv 15w40 are much more shear resistant.

How can that be, if the syn oils supposedly never shear away from that "hot" grade? I'm sure I'm misunderstanding something, so enlighten.............


Not quite. The 10w-xx is the cold performance target. The Xw-30 is the hot performance target. A base oil blend is selected that comes as close as possible (with the cost of doing so weighing in) to meeting both of targets and then VII's (and PPD's) are added to make up the difference. So you might have a 10w-20 that is VII'd into a 10w30 or a 15w30 that is "improved" to meet the 10W performance spec.

With synthetic base stocks it is common to be able to meet both those targets with just base stocks alone; no VII's. AMSOIL makes a 10w30 with no VII's and Redline makes a 5w30 with no VII's. The natural VI/multi visc characteristics of the base stocks allows it to meet both targets.

With regards to shear there is both temporary and permanent shear; temporary happening with the action of shearing forces in the engine that the polymers rebound from, permanent with the actual destruction of the polymer chains, eliminating their ability to expand/contract to affect viscosity.

With permanent shear (which it sounds like you are speaking of), the oil is brought back closer to the native viscosity characteristics of the base oil blend. What this lands you with will vary wildly depending on the constituents of that product. The results of permanent shear for example on a product like Mobil 1 Extended Performance 0w20, which is 70% PAO based will be markedly different than on a 0w-20 that is mostly group III based or a non-synthetic 5w-20.

Mobil's SM 0w-40 tended to shear down to a heavy 30 in service, becoming either a 0w30 or 5w30. The current iteration, which appears to leverage more PAO (around 50%) in its base oil blend is more shear resistant and generally stays in grade or very close to it.

Take a look at some of the Mobil Spectrasyn lo-vis PAO base oils to get an understanding of how good the cold performance of some of these products can be:

http://www.exxonmobilchemical.com/Chem-E...roductsservices

For example, the 10cSt product (10cSt @ 100C, 66cSt @ 40C, MRV 36,650cP @ -40C, CCS of 8,840cP @ -30C) meets the requirements for both the 10W and the SAE 30 designation as per this table:

So an oil could be blended using just that base oil with no VII's and be a 10w30. A combination of these types of base oils can be used to meet other intended viscosity spreads with very little VII being added.

great info, thanks.

 

[CT8]

Originally Posted By: MoreCowbellAz
I read a few articles, (including the oil univ series in BITOG), and I've seen that one of the differences between conventional and synthetic oil is that for example a conv 10w30 oil uses 10w base oil and adds VII to achieve 30w characteristics when hot, so when it shears that 30 w goes back towards the base 10w. Conversely, a syn 10w30 uses a 30w base and adds things the achieve the characteristics of a 10w when cold and supposedly doesn't shear away from that "hot" grade, so you don't have the shearing problem you see with conv oils.

So with that in mind, why all the talk of shearing out of grade of syn oils? I hear it all the time with the oils, particularly with the syn 5w40's and such, people claim the conv 15w40 are much more shear resistant.

How can that be, if the syn oils supposedly never shear away from that "hot" grade? I'm sure I'm misunderstanding something, so enlighten.............
The oil 101 series isn't totally factual.

 

[carbon12]

Originally Posted By: MolaKule
All oils have VII's added to bring them to their target viscosity spread.

Since synthetic bases oils have a naturally higher VI than mineral oils, they need fewer VII's.



Between conventional and synthetic is there any difference in the type or composition of the VII, or do they differ only by amount of VII added to the finished product?

 

[benjy]

nice write up overkill!! posters need to differentiate between oil groups as "synthetic" being deceptive, group III oils legally marketed as synthetic since 1999 is still a mineral oil, although its processing adds many benefits compared to dirtier lower group mineral oils. oil manufacturers are pretty "tight lipped" about their products + how they are formulated. lots of research + learning what certain terms mean helps enlighten us. as said above Amsoil's small engine oil is actually a 30 WT oil but meets the specs of a 10-30 WITHOUT any VII's Amsoil says little to no VII's depending on the viscosity + its spread i believe. from reading its said all mineral oils require more VII with a wider spread, say a 10-40 vs a 15-40, the 15-40 would be better as long as the lower number flows good enough in the temperature range your in. group IV synthetics flow better comparing with he same viscosity mineral oil, group III legally synthetic mineral oil flows better than other lower grades of mineral oil because its much cleaner with "most" of the waxes + other contaminants removed. Group IV + V oils never had any waxes or contaminants to remove as it is man made. i would like to know exactly what viscosity group IV synthetics start with for various blends, but i guess Amsoil is not going to tell me, but they do post more specs than others i have seen

 

[MolaKule]

Generally speaking for engine oils, they differ only in amount of VII added to the finished product.

Now there are different VII chemistries available for engine oils but the above will still hold true.

For ATF's and hydraulic systems, a different type of VII is used.