I know multi-visc oils are now currently pretty shear stable, but I wonder, do straight weight oils shear any at all?
Do straight weight oils shear at all?
- Thread starter gfh77665
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I, personally, believe the base-stocks could eventually deteriorate under heat and hard use, but I need to leave this one for those with knowledge.
Yep, they can shear down. In an engine its not normally a problem, but motorcycles with shared oil for the transmission too, can grind up those long molecules into shorter ones.
Base stocks essentially lose no viscosity by simply being sheared at rates that engines subject oils to. I searched for the Infinium study that showed this but couldn't find it.
A VI of 113 would mean it is using a group II base oil.
Originally Posted By: JAG
Base stocks essentially lose no viscosity by simply being sheared at rates that engines subject oils to. I searched for the Infinium study that showed this but couldn't find it.
Right, basestocks don't. But how many oils are only basestocks with no VIs?
Base stocks essentially lose no viscosity by simply being sheared at rates that engines subject oils to. I searched for the Infinium study that showed this but couldn't find it.
Right, basestocks don't. But how many oils are only basestocks with no VIs?
Originally Posted By: Gabe
Originally Posted By: dave1251
A VI of 113 would mean it is using a group II base oil.
Group II base oils can have a natural VI of 113?! That sounded pretty high to me.
Chevron's group II's have a natural VI of 102-118.
Group II+ (Pure Base;SOPUS, Isosyn;Chevron) are used to describe group base oils with a VI of 110-120.
I should of stated that in my original response that Valvoline could be using a group II+ base stock without any VII's.
Originally Posted By: dave1251
A VI of 113 would mean it is using a group II base oil.
Group II base oils can have a natural VI of 113?! That sounded pretty high to me.
Chevron's group II's have a natural VI of 102-118.
Group II+ (Pure Base;SOPUS, Isosyn;Chevron) are used to describe group base oils with a VI of 110-120.
I should of stated that in my original response that Valvoline could be using a group II+ base stock without any VII's.
Originally Posted By: RamFan
Originally Posted By: JAG
Base stocks essentially lose no viscosity by simply being sheared at rates that engines subject oils to. I searched for the Infinium study that showed this but couldn't find it.
Right, basestocks don't. But how many oils are only basestocks with no VIs?
Straight Weights...the topic line of this thread.
Originally Posted By: JAG
Base stocks essentially lose no viscosity by simply being sheared at rates that engines subject oils to. I searched for the Infinium study that showed this but couldn't find it.
Right, basestocks don't. But how many oils are only basestocks with no VIs?
Straight Weights...the topic line of this thread.
I am curently running Valvoline All Fleet Plus 30 ( picked up cheap!). in my Liberty CRD and my Kubota for the three summer months only. Neither engine has failed just yet. I plan on doing UOA when I change. Will try to post results from both.
Originally Posted By: gfh77665
I know multi-visc oils are now currently pretty shear stable, but I wonder, do straight weight oils shear any at all?
All oils can shear. ASTM 445 is the test - "Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)" - for any oil, while D5275 is a test for oils with a polymer in it.
ASTM 445 http://www.astm.org/Standards/D445.htm
However, in normal use shear in an automobile engine is normally not an issue.
I know multi-visc oils are now currently pretty shear stable, but I wonder, do straight weight oils shear any at all?
All oils can shear. ASTM 445 is the test - "Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)" - for any oil, while D5275 is a test for oils with a polymer in it.
ASTM 445 http://www.astm.org/Standards/D445.htm
However, in normal use shear in an automobile engine is normally not an issue.
Originally Posted By: Zako2
It would have been interesting to do a summer OCI on a straight 30 grade dyno oil, which are widely available, and post a UOA. Perhaps this would work well on a car that commutes long distances.
I did one over a year ago on Service pro SAE 30 in my '78 Granada.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2679111&page=1
It would have been interesting to do a summer OCI on a straight 30 grade dyno oil, which are widely available, and post a UOA. Perhaps this would work well on a car that commutes long distances.
I did one over a year ago on Service pro SAE 30 in my '78 Granada.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2679111&page=1
Even so called straight weight oils still contain a DI package that can make up to 25% of the volume of the oil.
The add' pac' is usually quite viscose due to the polymer based dispersants which will increase the VI the finished oil over and above that of the base oil. These dispersants are generally quite shear stable but not totally impervious to shear under the right conditions.
So yes if an oil contains no additional polymer VIs it will be very shear stable in service usually to the point that oxidative oil thickening will be evident over long OCIs, particularly with mineral oil.
The add' pac' is usually quite viscose due to the polymer based dispersants which will increase the VI the finished oil over and above that of the base oil. These dispersants are generally quite shear stable but not totally impervious to shear under the right conditions.
So yes if an oil contains no additional polymer VIs it will be very shear stable in service usually to the point that oxidative oil thickening will be evident over long OCIs, particularly with mineral oil.
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