Are you disappointed in the shear stability of most 5w30's?

[buster]

Given that fuel dilution cannot - arguably - be prevented or mitigated by the choice of oil, is it a stretch to worry or seek the oils with the least possible shear? Honest question.

LOL It's not something to worry about. I think it's worth considering in some cases. The majority of people don't. The engineers that design the engine and oils know best.

Generally speaking, an oil with less VII's and a high quality base oil will retain its viscosity better than a less quality oil.

 

[OilReport99]

The majority of people don't.

Thanks

 

[TheLawnRanger]

Shear Terror

 

[SR5]

Right now I’m running a 5W-30 that’s rated ACEA A3/B4 (full SAPS) which means it must pass the KO30 shear stability stay-in-grade test. Similar with a Euro C3 (mid-SAPS) rated 5W30 like M1 ESP or any Dexos2 (not D1G2) oil, they need to pass the KO30 shear stability test.

 

[kschachn]

Given that fuel dilution cannot - arguably - be prevented or mitigated by the choice of oil, is it a stretch to worry or seek the oils with the least possible shear? Honest question.

Mechanical shear and fuel dilution aren’t the same thing. Yes fuel can cause what appears to be temporary shear, but the only way to combat fuel dilution is an early OCI or a higher grade.

 

[ChrisD46]

It would be an interesting topic - if I didn't have a GDI engine ... My OCI is 5K miles max so I don't worry about my 5W30 synthetic oil viscosity dropping .

 

[rob1715]

Don't know, but I've seen too many valve covers taken off and with a synth oil and good filter with good OCI and the cams look just as perfect as the day it rolled off the assembly line after 150k miles. 5 - 7k mile OCI and don't worry about it.

 

[Patman]

One of the reasons why I love the Mobil 1 ESP Formula 5w30 that I'm using in the Corvette is because it holds it's viscosity extremely well. On my last UOA, after 7400 miles, the viscosity was 12.0 cst at 100c, Mobil 1's specs for new is 12.1.

 

[buster]

Mobil 1 ESP is top notch.

Call your local doctor if you experience anxiety of VII Shearing Disorder.

 

[buster]

Been reading about VII's. Dont know much so I'm piecing things together as I go.

Prior gen Mobil 1 and even some other ILSAC 5w30's would drop out of grade pretty quickly. There could be a reason why though. If they use a low viscosity base oil, and thickened it with a small amount of a "weak" polymer, then that's not necessarily a bad thing. This could be what Mobil does, which is why you see it drop out of grade. The Hansen solubility parameter of an oil will be very good as a result especially if they are using AN's, which for prior SN version of Mobil 1 it was suggested they use 10% AN.

The lower the viscosity of the base, the higher the Hansen solubility parameter.

If you use a low-viscosity base, which had to be thickened with a weak polymer, you won't have to add as much of it.

The stronger the polymer, the more it needs to be added.

OCP polymers are unstable, but work strong at low doses to "thicken" from what I read.

The Hansen Solubility Principles and its Relation to Varnish

Typically, when we think about varnish, our thoughts move towards large pieces of equipment. However, due to the nature of varnish, it usually affects the smaller (or tighter) component clearances first which in turn cause the entire machine to fail. One such component is Hydrogen seals usually...

www.fluitec.com

 

[buster]

In China they openly state they use mPAO. LOL