Many UOA show vis loss. New norm?

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Not gross viscosity loss but just enough where that xw30 is now an xw20 per se. Most of these are glossed over by Blackstone as insignificant. Is this as normal as Blackstone would have us believe?
 
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They oils in question tend to have one thing in common I think. The old days it was dino oils with lashings of VII, now (typically) it's GrIII oils with ultra high VIs. Also, 20s used to "stay in grade" because the grade went so low...now they get the same treatment as the 30s.
 

wemay

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So 20s are no more shear stable than a 30 'anymore'? Or any other weight, for that matter.
 
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It certainly seems that the 20 grades used oil analysis that have been posted lately have shown shear. Wasn't there a used oil analysis posted of a sustina product in a 30 grade flavour that sheared into a 20 grade in 4000 miles. That doesn't instill much confidence extending the interval,does it? Wear seems consistent in most cases,nothing extraordinarily high anyways but can we expect that it'll stay that way? I don't know?
 

wemay

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It seems that on one hand, we are using more fuel efficient lower vis oils in newer technology engines that, on the other hand, don't allow for extended intervals due to dilution or shear. Hence, coming full circle in energy use but substituting oil for gas. Of course, this is predicated on the belief that said shear or dilution is detrimental to engine life.
 
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That is why I like to start off with a grade or two heavier than necessary. Every now and then I don't get to those two 2013 Matrix and they will go 12,000 miles without an oil change. I would worry about that if I used 5W20, but xW40 would have to shear a long way to be a concern. Have I checked my work with UOAs? Yes. Do I worry about 3% fuel economy on a couple of puddle-jumpers? No. Do I get my money's worth from the oil? Yes. Do I care what anybody else thinks? No. If someone else wants to pay for those vehicles will I use their choice of oil? Yes.
 
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Originally Posted By: Clevy
It certainly seems that the 20 grades used oil analysis that have been posted lately have shown shear.
I have not been paying very close attention to everyone's latest UOA results, but Blackstone shows the "normal" cSt viscosity @10°C range for a 20 on all of my UOA reports to be 6.0 - 9.7. Mine have ranged between a low of 7.49 and high of 8.41 with average somewhere in the 7.7x slot. How much loss is considered shear (an honest question)?
 
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I don't follow UOA's closely. Is there a connection between oil shear and DI in the UOA's that you viewed prior to posting? Thanks..
 
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Certainly High Shear is the spec that you need...you just don't/ can't measure that with a UOA. This discussion had some great information, in that Supertech had a high shear 100C test included...you can see that's nearly 4cst off the KV100 for that particular oil...and the hths is pretty solid for a 5w30. Temporary viscoisity loss is the difference between the KV100 and High shear 100, assuming the KV100 comes all the way back each time. Permanent loss is the fact that the KV100 and the HTHS 100 don't recover (polymeric shearing) http://papers.sae.org/801390/
Quote:
The relationships between the permanent and temporary viscosity losses were examined for 43 oils at 100°C and 150°C. High-shear-rate viscosities were measured at a shear rate of 10⁶ s\u-₁ in a capillary viscometer for new oils and used oils. New oils that had been subjected to 20 cycles in the Fuel Injector Shear Stability Test were considered to be used oils in this program. There was no useful relationship between the temporary viscosity loss (difference between kinematic and high-shear-rate viscosities of new oil) and the permanent viscosity loss (difference between kinematic viscosities of new oil and of used oil). Also, there was no useful relationship between either the temporary or permanent losses alone and the combined loss (difference between kinematic viscosity of new oil and high-shear-rate viscosity of used oil.) There was, however, a relationship between the temporary loss and the permanent loss, used together, and the combined loss. This relationship makes it possible to estimate the combined viscosity loss without having to measure the high-shear-rate viscosity of the used oil.
 

wemay

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Originally Posted By: demarpaint
I don't follow UOA's closely. Is there a connection between oil shear and DI in the UOA's that you viewed prior to posting? Thanks..
A general view of recent uoa but I'm sure with a subconscious lean towards d.i. In particular, due to my vehicles and that most newer vehicles are d.i. I must say though, very few showed dilution severe enough for a red flag but very few also extended the oci/uoa past ~5-7k miles. Shannow, nice link. Thank you.
 
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Yes it is normal, and it is not new. Vis loss is a characteristic of resource conserving, and before that energy conserving oil. Containers are marked with ISLAC gf4 or gf5 or gf6, and "for gasoline engines" see images . Oil then returns to correct viscosity after 4000 or so miles.
 
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If the manufacturer spec oil and grade are used within the recommended OCI and shearing occurs then it is amost guaranteed that this was taken into account when the recommendations were created. If so it is a non-issue and worrying about nothing.
 
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Fuel dilution from DI doesnt help. You can have a 9.5cst 5w20wt it sheared to 7.5 but "stayed in grade" Then you have a 10.5cst 30wt that sheared less...to 9.2cst and its "out of grade" The whole oil viscosity "grade/wt" terminology is obtuse.
 
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viscosity index can be easily "propped up" but a higher shear indicated a stronger oil. noack which is burn off is important especially in DI engines as the vapors can deposit on the top of the valves. real group IV + V oils have noack's in single digits especially 10-30 my favorite. look at Amsoil signature series 0-20 is 9 but a 5-20 is 5.5 + 10-30 is 5.3 with a HTHS of 3.2, really good stuff. unless your below 0 most of the time a 5w or even 10w real synthetic will flow well + protect better
 
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