5w30 is thicker than 10w30

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He has the right idea - cold oil is thicker than hot oil (some people still try and argue the reverse); He just doesn't understand how the SAE numbering system for oil works.

:edit: I think!
lol.gif
I'm getting a head ache trying to understand his logic.
 
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Often a virgin 5W30 will start thicker than 10W30 but due to shear will become thinner after use. Often a 5W30 will shear into a 5W20.
 
Ha I see this at least twice a week at work. Not much you can do , you can argue till you turn blue. Best thing to do is let it go and let them think whatever they think. I once had a old timer lose his mind when I suggested using 5w-20 for a 4.6 2v modular. He was literally screaming that unless you use a 20w-50 in every motor it was doomed too immediate bearing failure. Basically some people you cant reach.
 
Originally Posted By: dave1251
Often a virgin 5W30 will start thicker than 10W30 but due to shear will become thinner after use. Often a 5W30 will shear into a 5W20.


O I understand that, but I'm just using face value without getting too BITOG oil nerdy on the guy.
 
Originally Posted By: Drew99GT
He has the right idea - cold oil is thicker than hot oil (some people still try and argue the reverse); He just doesn't understand how the SAE numbering system for oil works.

:edit: I think!
lol.gif
I'm getting a head ache trying to understand his logic.


I used to be a huge poster on there, but pulled back a bunch when I was sans Mustang. The problem there is the whole automotive world according to them revolves around Mustangs. Nothing wrong with that, they are great cars, but they will collectively stick their heads in the sand when I mention that my Volvo in stock form has more HP than most of their cars.
 
Yes that Kurt guy is pretty confused.

bdcardinal, btw, the first number of an SAE oil grade is not measured at 0C but much colder than that.
It's at -35C for a 5W and -30C for a 10W.
 
Originally Posted By: CATERHAM
Yes that Kurt guy is pretty confused.

bdcardinal, btw, the first number of an SAE oil grade is not measured at 0C but much colder than that.
It's at -35C for a 5W and -30C for a 10W.


Ahh thanks for the heads up on that, always thought it was 0C, either way its cold for someone from Santa Barbara haha.
 
Well my theory on this is due to stay in grade requirements a 5W30 needs to be thicker to counter shearing due to the increased use of VII's. So the best I can help you is that yes 5W30's tend to be thicker until shearing overcomes additional viscosity. Once this happens a 5W30 is significantly thinner than a typical 10W30 often a grade thinner. Hope this helps.
 
Wow that guy lives in opposite world! What his claims were about the 5w-x and 10w-x were opposite, then, what he said you were saying was the opposite of what you were actually saying! Maybe he is from Htrae (Earth backwards) where Bizarro and Bizarro Lois live. It seems that maybe he was using the wrong test standard astmd88, doesn't the API use ASTMd445 test to indicate viscosity? Anyhow I try to refer people to this site as often as I can. I tell them that you will find all sorts of "factory oil fans" ie Castrol, Valvoline, Pennzoil, Amsoil, etc... but generally they try to stay honest in there recommendations for someone who is asking about different types of specs in the different oils. More reason that I appreciate this resource.
 
Originally Posted By: dave1251
Well my theory on this is due to stay in grade requirements a 5W30 needs to be thicker to counter shearing due to the increased use of VII's. So the best I can help you is that yes 5W30's tend to be thicker until shearing overcomes additional viscosity. Once this happens a 5W30 is significantly thinner than a typical 10W30 often a grade thinner. Hope this helps.

Since when do Viscosity index improvers cause shearing?
 
You should have mentioned that many, maybe most 10W-30s are thinner at 100C than 5W-30s of the same brand.
That would have really blown his mind.
You might have brought in the fact that the 5W-30s always have higher VI than same brand 10W-30s.
Information overload.
You hear this kind of thing about oil grades and oil in general everywhere.
I bought a jug of Nextgen Maxlife 10W-40 at a local O'Reilly's last Saturday.
FAR is always a good thing with an oil that's given good results.
The counter guy told me that he would never use Valvoline and prefered GTX.
I told him that the two brands had virtually identical formulas, although Maxlife has some moly and maybe 30% Grp III, while GTX doesn't.
I also told him that I'd had the cleanest UOA I have ever seen from any BMW at any mileage on a short 4K run of Nextgen Maxlife 10W-40.
Gave him something to think about.
 
Originally Posted By: skellyman
Originally Posted By: dave1251
Well my theory on this is due to stay in grade requirements a 5W30 needs to be thicker to counter shearing due to the increased use of VII's. So the best I can help you is that yes 5W30's tend to be thicker until shearing overcomes additional viscosity. Once this happens a 5W30 is significantly thinner than a typical 10W30 often a grade thinner. Hope this helps.

Since when do Viscosity index improvers cause shearing?



They don't cause it, they are broken into smaller chains by shearing. Perhaps someday they'll come up with a VI improver which is shearproof.
 
Originally Posted By: skellyman

Since when do Viscosity index improvers cause shearing?

Since forever?
What's why oils sheer out of grade, their VIIs have sheered apart (broken up into pieces).
 
as to the OPs posts on the other forum, this is pretty common. Gotta shrug it off. Most people don't understand the SAE grade system. It's confusing and non-intuitive. I was under the same impression as the poster in the other forum for years until I found BITOG. Motor oil university (MOU) straightened me out.. and the fact that when I looked on the major oil companies web sites, they all agreed with the MOU and all the random forum posts from owner/enthusiast forums did not.
 
Originally Posted By: DireStraits
I don't mean to hijack the OP's thread, but can someone explain shearing to me.


Nevermind, I found an article on here.
 
Quote:
Perhaps some day they'll come up with a VI improver which is shearproof.

They already have to the point that even the most advanced race oils now use some polymer thickeners.
There are many different types of VIIs but the only way to know how effective any particular oil is at retaining it's original viscosity in service is to test it.
For example, in OTC oils, Pennzoil is known to use high quality VIIs as their synthetic oils are quite shear stable.
 
Originally Posted By: GearheadTool
Just remember.. Mobil is the best.
whistle.gif



Its Mobile according to most forums, gave up that argument long ago.
 
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