Oil shear?

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Is there any evidence that lower cost synthetic oils (ST, Form Shell, Parts Master, Etc,) shear down faster then the so called top tier oils (M1, PP, Amsoil, etc) of the same oil weight?
 
Originally Posted By: NStuart
I'm in


Me too. I have no evidence but this will be interesting if someone does.
 
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Its been covered as far as higher-spec oils vs. SN GF5 dexos1 oils.
Of course the missing info is which brands and types of oils use which type of VII chemicals.
http://hrcak.srce.hr/file/37720
Looks like any oil using OCP as the VII best passes the toughest shear tests (Shear Stability CEC L-14-93, ASTM D6278 / 7109).
Mercedes MB 229.5 rated oils, Euro-specs. ...
dexos1 doesn't appear to run the shear test as long as the Euro-spec oils do.

Conclusions from http://hrcak.srce.hr/file/37720 :
1. New international specifications ACEA and API require that the shear stability of
engine oils is tested by 90 cycles of oil passing through the nozzle instead of
current 30 cycles; these requirements are accepted by a number of vehicle
manufacturers.
2. Shear stability determination according to new ASTM D 7109 method has been
defined with 90 cycles of testing.
3. Different concentrations of viscosity index improvers are needed for production
of multigrade engine oil of the same viscosity; the highest additive concentration
is needed for the viscosity index improvers based on OCP.
4. Viscosity index improvers based on OCP have the best shear stability after 90
cycles of testing.

5. Engine oil with the viscosity index improver based on styrene-isoprene (C) has a
significant viscosity loss after extended testing from 30 cycles to 90 cycles and it
does not meet requirements of the new international and OEM specifications.


https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1172315
 
Last edited:
Originally Posted By: Camprunner
Is there any evidence that lower cost synthetic oils (ST, Form Shell, Parts Master, Etc,) shear down faster then the so called top tier oils (M1, PP, Amsoil, etc) of the same oil weight?


The more important underlying question:
Does it matter if they do?

The lube does not exist to be self-serving. It's there to protect the engine. So if there is some shearing (moderate, not obscenely out by two grades), does it affect wear? After all, that's the purpose of the lube; to reduce wear. I've seen a lot of UOAs, and I've never seen one where shearing (or ox thickening for that matter) affects much of anything when we're only talking about typical shifts in grade. Some oils have less room for vis loss; where an engine using a 10w-40 can easily tolerate a drop to 30, I'd not want a 5w-20 to drop to a 10.

But the thing to ask is if the shearing actually causes an effect?
How will you know? Run the lubes and find out.

I doubt you're going to see much disparity in the actual protection factor; that's their job after all, and that's what you should judge them on.
 
Originally Posted By: Camprunner
Is there any evidence that lower cost synthetic oils (ST, Form Shell, Parts Master, Etc,) shear down faster then the so called top tier oils (M1, PP, Amsoil, etc) of the same oil weight?


No, none, zip,. zero, not a concern.
Top tier = think of top marketing
 
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