brand x oil is thinner than brand y oil question

[Triple_Se7en]

Originally Posted By: Shannow
Originally Posted By: OilUzer
but this is where it get interesting (at least for me) ...
he said that some 0W oils can be thicker than a 5W of the same grade except at very low temperatures ...

i need to corner him again about the above statement since it initially confused me but I can now picture how it can happen. it raised another question for me regarding the graphs and linearity etc. which i may ask in another thread.


0W 40 will be typically thicker than a 5W20...except at the limits of pumpability.

Yes, an oil that narrowly misses 0W would have to be labelled as a 5W...the oils HAVE to be labelled the lowest grade that they meet.

If they don't make 0W, they can't be labelled that, and will never be labelled 2.5W, in spite of how fuzzy it makes you and your chemist friend feel.


Our backyard chemists have it correct. For if it is 2.5W, then it can't be 5W.
Stupid regulations say it must be 0 or 5. But only a few years ago, those regulators disallowed the number 16.

Someone needs to disallow those regulators - or at least make them take 10 classes (Human Lie Detector 101).

 

[kschachn]

Originally Posted By: Triple_Se7en
Our backyard chemists have it correct. For if it is 2.5W, then it can't be 5W.
Stupid regulations say it must be 0 or 5. But only a few years ago, those regulators disallowed the number 16.

Someone needs to disallow those regulators - or at least make them take 10 classes (Human Lie Detector 101).

Regulators?

 

[ZeeOSix]

As a few have eluded to, forget the "SAE viscosity rating bands" that "classifies" an oil "weight".

If you measured and plotted any oil's viscosity vs temperature you'll get a curve. If you have a 5W-30 that is viscosity A at temperature X, and have a 10W-30 that is viscosity B at temperature X , then you will get an oil that is viscosity G at temperature X when you mix them together. The ratio of the mix will determine the viscosity D at temperature X.

Originally Posted By: OilUzer
now my main question:
when people say brand x 5W-30 is "thinner" than brand y 5W-30 ... is it because of the reason above (oil A vs. B)
or am i over-simplifying things?


When someone says Oil A (5W-30) is "thinner" than Oil B (5W-30) it means that Oil A is thinner at temp X than Oil B, even though they both fall into the same "SAE weight rating band".

 

[ZeeOSix]

Corrected my statement above - timed out for an edit.

If you measured and plotted any oil's viscosity vs temperature you'll get a curve. If you have a 5W-30 that is viscosity A at temperature X, and have a 10W-30 that is viscosity B at temperature X, then you will get an oil that is viscosity C at temperature X when you mix them together. The ratio of the mix will determine the viscosity C at temperature X.

 

[gfh77665]

Originally Posted By: OilUzer

There is no spec/designation for 6,7,7.5,8W etc. only 0W, 5W, 10W ... at least for auto oil.


Not correct. There is a 4, 8, and 16 oil. For some reason, some people here will flip out if someone mentions a "7.5", but won't blink if a 4 or 16 is mentioned.

Personally, I easily get the meaning of a "7.5", even if its not technically official. Too many others cannot see the forest for the trees, so they can't process the "7.5' concept. Their brain overloads, apparently.

 

[kschachn]

Originally Posted By: gfh77665
Originally Posted By: OilUzer

There is no spec/designation for 6,7,7.5,8W etc. only 0W, 5W, 10W ... at least for auto oil.

Not correct. There is a 4, 8, and 16 oil. For some reason, some people here will flip out if someone mentions a "7.5", but won't blink if a 4 or 16 is mentioned.

Personally, I easily get the meaning of a "7.5", even if its not technically official. Too many others cannot see the forest for the trees, so they can't process the "7.5' concept. Their brain overloads, apparently.


Actually what too many others can't comprehend is the "W" rating and how it differs from the other number.