Does 5w30 really generally sheer down to 20 wt?

[JAG]

Originally Posted By: mechtech2
I don't see patterns like that from the UOAs on this site.
Using the UOA data from this site to compare shear stabilities of different conventional 5W-30 oils is like trying to measure a dimension to the nearest one-thousands of an inch with a tape measure.

 

[edhackett]

...with a tape measure. With all the numbers rubbed off.

 

[TallPaul]

I guess it depends on how Valvman's test was set up. Ideally a sample of 30 or more observations on each oil gives the best statistical results. I would think they should get many bottles of each oil (preferably from different batches) and run the test multiple times per oil brand (preferable 30 each again, else need more rigorous statistical assumption testing). One may find some brands have a lot of variation between batches; others may be much tighter.

It's great having Valvman here. Now if we can get him to tell us how much PAO in Synpower, Maxlife, etc. If the test results presented so far are an accurate representation of the actual situation, then I am very pleased as Valvoline is my favorite brand and if the basic Valvoline is that good, think how wonderful Maxlife and others should be.

 

[INDYMAC]

This 5W30 shearing to 20W at 100C phenomena is not just limited to 5W30 SM dino oils. I've been noticing this with 10W30 SM dino and synthetic oils lately too. Here is a discussion thread of shearing with 10W30 M1 on a S2000 (not known to shear or thicken oil) board:

http://www.s2ki.com/forums/index.php?showtopic=558202

I recently did a UOA on Schaeffers #703 10W30 that showed a 9.2cSt @100C after only 4384 miles in a 2UZ-FE Toyota engine. Even though I had 1.46% fuel dilution, Terry said it sheared "by design". I've heard inference to this term before, but don't know exactly what it means. I suspect that it refers one of the many ways that oil companies can engineer an oil to qualify for an energy conserving seal of approvement...smoke and mirrors!

 

[buster]

Originally Posted By: Valvman
About a year ago Valvoline conducted a survey of various 5W-30 conventional products on shear stability and stay-in-grade performance. We went to our local Advance Auto Parts and purchased quarts of the products listed below. We noted that each product was currently labeled with the API SM donut and carried the ILSAC GF-4 starburst. I have included the results of the ASTM D6278 Kurt Orbahn (Bosch diesel injector) test which is typically used to evaluate stay-in-grade shear performance for engine oils. The current API requirement for BOI or VGRA (baseoil interchange or viscosity grade readacross) purposes for a 5W-30 stay-in-grade limit is 8.5cSt. Any 5W-30 that shears below this viscosity does not meet this API requirement for BOI or VGRA. The 8.5cSt viscosity limit is actually below the SAE J300 lower viscosity limit of 9.3cSt. for a SAE 30 grade because the Kurt Orbahn test is more severe than the Seq VIII engine test used to evaluate shear stability when running an API oil licensing program. European ACEA requirements are more severe requiring a higher performance level and a stay-in-grade pass uses the SAE J300 viscosity lower limits. So a 5W-30 must retain a minimum of 9.3cSt after the test. Out of all the oils tested, only the Valvoline oil showed the ACEA level of stay-in-grade performance.

Product Name Valvoline Premium Conv, Castrol GTX, Havoline,Mobil Clean 5000, Quaker State, Pennzoil
SAE Grade all 5W-30
Kinematic Viscosity @40C,cSt: 60.17, 60.59, 54.90, 60.16, 62.46, 61.07
Kinematic Viscosity @100C,cSt: 10.66, 10.59, 9.71, 10.55, 10.43, 10.49

ASTM D6278 Kurt Orbahn Shear (30 pass)
Kin Vis @ 100C, cSt after Shear: 9.42, 9.04, 8.89, 8.8, 8.68, 8.63





Good to know, thanks!

 

[Smokescreen]

So does a 20wt ever shear down into what would be 10wt territory?

 

[1sttruck]

"....We noted that each product was currently labeled with the API SM donut and carried the ILSAC GF-4 starburst.....Out of all the oils tested, only the Valvoline oil showed the ACEA level of stay-in-grade performance."

Which ACEA rating ? Looking for A5/B5 seems to be a simple way to pick a robust 5w30.

 

[jmsbntz]

Originally Posted By: TallPaul
This statement frequently pops up on this site, but I don't believe it. Yet, if true, it just gives me one more reason to support my aversion to 5w30.

Looking at the last couple pages of gasoline UOAs show that many engines/operating conditions still shear some conventional and synthetic oils to the next lower grade. Given a choice I would rather have my oil thin to the upper range of the next lower grade instead of thickening. Although I've not seen convincing evidence of accelerated wear (thicker or thinner) with a reasonable OCI. At least not unless other factors (fuel, silicon, coolant etc.) were in the mix.

With that said I would not be comfortable using 0W, 5W20 oils if they sheared to 10 wt... but they don't!

Code:


Havoline 10W30, 8.81

M1 5W30, 9.26

Amsoil 5W40, 11.56

Castrol GTX 5W30, 9.01

Valvoline Synpower 5W30, 8.94

M1 0W40, 11.97

Motomaster F1 5W30, 9.09

PP 5W30, 9.08

QS 5W30, 8.77

Castrol Syntec 5W40, 11.89

 

[buster]

bump