THANKS G MAN this is the info I was looking for I knew it referred to a test but did not remember what it was.
I also knew it would show that a lot of people have a misunderstanding of the W
The Meaning of W
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I also knew it would show that a lot of people have a misunderstanding of the W
Okay, nevermind what I said then.
G-Man's post is the ONLY correct response in this whole thread. It's the only post that actually answers the OPs question.
Pablo's post also contains a link to the correct answer, but the information may be a little thick for someone to wade through, especially someone asking such a basic (but perfectly valid) question. I too asked this same question a few years ago.
Pablo's post also contains a link to the correct answer, but the information may be a little thick for someone to wade through, especially someone asking such a basic (but perfectly valid) question. I too asked this same question a few years ago.
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This explanation, using 10W-30, always falls apart when 0W-30 is substituted as the viscosity grade.
Example;
0w-30=
"The viscosity of SAE 0 when cold." (What is a SAE 0???)
"The viscosity of SAE 30 when hot."
And, substituting 0W-30 for 10W-30 in this statement:
"A 0W-30 will start out as a 0 weight when cold and then thin down to the viscosity of a 30 weight when hot." (Again, what is a 0 weight oil???)
Also, I make every attempt to keep the "thin" term out of an explanation of viscosity per the J300 chart, and use the phrase "less thick" instead.
It's amazing how many readers have wrongly assumed that an oil is thin at cold temps and thick at hot temps because someone tossed out the "10W-30 means thin like a 10 weight in cold and thick like a 30 weight when hot" explanation for the SAE viscosity grades.
Glad you edited your response, personally I find a portion of G-man's accurate and precise answer a bit thick for someone who simply asked what the "w" means. TMI.
This MAY put a newbie's head in a spin........dunno......
Quote:
Okay, nevermind what I said then.
Technically, you're wrong! You said SAE10..................should have said SAE 10W.
The reason 10w-30 seems odd when oil thins with temperature is the fact that the 10W part of the equation is not the same measurement as the 30 part of the equation. Like G-Man indicated, anything before W relates to cold cranking at cold pumping, where as the 2nd number is the actual measured viscosity of the oil at 100 degrees C.
so why isnt oil labeled with kinematic viscosity instead of the stupid w?
look at it like this. w has failed. ask almost ANY mechanic or end user what the w means, and they will all get it completely wrong. heck this is an oil website and most of us got it wrong.
the w was made to try and make things easier,. but i believe it has failed. i think we should label oils with a cold and hot kinematic viscosity and ditch the useless w.
would a 10w30 becomes a 30-12?
look at it like this. w has failed. ask almost ANY mechanic or end user what the w means, and they will all get it completely wrong. heck this is an oil website and most of us got it wrong.
the w was made to try and make things easier,. but i believe it has failed. i think we should label oils with a cold and hot kinematic viscosity and ditch the useless w.
would a 10w30 becomes a 30-12?
No, that's not what I said and that's not correct. The number to the right of the "W", e.g., 30, 40, etc. has NO MEANING whatsoever as far as viscosity apart from the RANGE of viscosity listed for that number on the J300 table. Thus a 10w30 oil is one that meets the cold cranking and cold pumping specs of a 10W and has a viscosity (cSt) of between 9.3 and 12.49 at 100C AND has a HTHS vis of at least 2.9 cSt.
Well, it really is a moot point to you since you think running SAE 30 through winter is a good idea.
Wrong, wrong, wrong!
simply because the W is an archaic, disproportionate, irrelevant rating character. When oil was first discovered 55 million years ago, the engine mechanics of that time had use of oil that performed like lightly refined crude, Grp S oil. Some guys would pour 50wt, Grp S oil in their crankcase for the winter and destroy them.
And where is my response incorrect?
MolaKule
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monogrades are the only true "weights" ..the rest are merely impostors at the 100C spec. I think that G-Man makes this distinction between mono and multi grade oils.
In that Wikipedia article they state …
" … …For single-grade oils, the kinematic viscosity is measured at a reference temperature of 100 °C (212 °F) in units of mm²/s or the equivalent older non-SI units, centistokes (abbreviated cSt). Based on the range of viscosity the oil falls in at that temperature, the oil is graded as an SAE number 0, 5, 10, 20, 30, 40, 50, 60 or 70. The higher the viscosity, the higher the SAE grade number is. ……"
Just what are the viscosity ranges for 0, 5, 10 … …grades? Don't see them on any chart.
" … …For single-grade oils, the kinematic viscosity is measured at a reference temperature of 100 °C (212 °F) in units of mm²/s or the equivalent older non-SI units, centistokes (abbreviated cSt). Based on the range of viscosity the oil falls in at that temperature, the oil is graded as an SAE number 0, 5, 10, 20, 30, 40, 50, 60 or 70. The higher the viscosity, the higher the SAE grade number is. ……"
Just what are the viscosity ranges for 0, 5, 10 … …grades? Don't see them on any chart.
0W: at least 3.8 @ 100C*
5W: at least 3.8 @ 100C*
10W: at least 4.1 @ 100C*
20W: 5.6 to 9.29 @ 100C
*There is no upper limit for 0W, 5W, and 10W. J300 only lists a minimum vis @ 100C for these grades. This is why Valvoline 10W can have a 100C vis of approx 6.5 (which is technically a 20W) but is labeled as a 10W because it meets the cold cranking and cold pumping specs for a 10W.
The answer is 42
So let me see if I get this straight, for sake of example, say a 10W30 is what I have in mind. At a temperature of 20 degrees fahrenheit (average winter temps around here) the number 10W means it's thicker than a SAE30 at that temperature? It seems misleading but I think I got that right...
10W is thicker than SAE 30 at colder temps?
10W is thicker than SAE 30 at colder temps?
It doesn't answer the OP's question. You didn't say anything incorrect Paul; sorry to imply otherwise. But in terms of a correct response to the original question, G-Man and Pablo are really the only ones to do so.
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