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#131674 - 04/27/05 08:55 PM So what does "W" mean
ozzman_g7com Offline


Registered: 04/27/05
Posts: 2
Loc: Mexico
Hi, I was looking the other day on motor oils, and I saw a 10W30, and I
thought "What did the W stand for", I have heard that W means winter,some say weight, and
others say that it is just a designation that means how the oil acts on low
temperatures, so what does it mean?
I made a search but didn't find anything about it, I'm new here but I think this was covered before, I just couldn't find it, thanks.

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#131675 - 04/28/05 09:01 AM Re: So what does "W" mean
wavinwayne Offline


Registered: 01/06/05
Posts: 7522
Loc: North Alabama
[Welcome!] ozzman

In 10W-30 oil, the two numbers mean it is a "multiviscosity" or "multigrade" oil that is effective over a range of temperatures. The first number, 10, is an index that refers to how the oil flows at low temperatures. The second number, 30, refers to how the oil flows at high temperatures. The W designation means the oil can be used in winter.

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#131676 - 04/28/05 09:21 AM Re: So what does "W" mean
ozzman_g7com Offline


Registered: 04/27/05
Posts: 2
Loc: Mexico
http://members.rennlist.com/oil/motor%20oil%20101.htm
At chapter 7 the first sentence says otherwise?
[I dont know]

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#131677 - 04/28/05 09:56 AM Re: So what does "W" mean
blupupher Offline


Registered: 08/27/04
Posts: 1874
Loc: Katy, Republic of Texas
First paragraph on Valvoline's site says "W" stands for winter.

HERE

quote:
Most people are familiar with oil's viscosity rating10W40, for example. However, very few may know that the "W" refers to "winter," not "weight." ...

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#131678 - 04/27/05 10:00 PM Re: So what does "W" mean
Gary Allan Offline


Registered: 09/28/02
Posts: 39806
Loc: Pottstown, PA
As much as I admire the esteemed Dr. Haas and his access to high caliber resources, the notion that SAE/API skipped all the letters between A and V and settled on "W" as the denotation of cold cranking specifications/ratings of multi-visc oils and having it in no way, shape, or form imply "winter" ..is a little hard to buy. But I do believe that someone told him this.

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#131679 - 04/27/05 10:23 PM Re: So what does "W" mean
Drew99GT Offline


Registered: 10/11/02
Posts: 20887
Loc: Colorado Springs
The W DOES mean winter for multi-viscosity oils, and the number preceeding it designates the cranking viscosity at a particular low temperature (which is entirly different than how the "higher" number is measured, it is the kinematic viscosity at 100C). -25C for 10W, -30C for 5W, -20C for 15W etc. In essence, that is the lowest temperatures for each W number that you'd ever want to start an engine with (10 degrees higher is definetally a safer limit and they specify MRV pumping viscosity limits for each W number 5C lower than the cranking limit so that if an engine does start and will crank with a particular viscosity, the oil will pump.) For each W number and corresponding temperature, the maximum allowable cranking viscosity at that temperature is around 7,000 centipoise (at least for 5W and 10W).

[ April 28, 2005, 01:32 PM: Message edited by: Drew99GT ]

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#131680 - 04/27/05 10:28 PM Re: So what does "W" mean
Blue99 Offline


Registered: 09/27/03
Posts: 2233
Loc: Wisconsin
While "W" may be just a letter as DR Haas has contended, the origins are from the early 50's and are probably no longer important.

For most of us, "W stands for Winter" works just fine, and avoids the confusion with the term "weight"

Read 10W-30 as "10 dub ya 30" and not "10 weight 30".

The common definition of a 10W-30 being a 10 weight at cold temperatures and a 30 at full operating is inaccurate. The 10W rating is a cold temp viscosity limit and is not meant to reflect the cold flow viscosity of a 10 weight oil.

This common explanation falls apart when applied to a 0W-30 oil, as what exactly would be the viscosity of a 0 weight oil under the current SAE J-300 system of classifying oils?

Reference The Infineum SAE J-300 Viscosity Chart to view the W low temperature ratings.

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#131681 - 04/28/05 12:38 AM Re: So what does "W" mean
Stinky Peterson Offline



Registered: 05/15/03
Posts: 383
Loc: Bismarck, North Dakota
Another variation:

If there is only one number (SAE 20) it means the lubricant viscosity falls within the viscosity band for 20 weight oil at 100C (212F), sometimes called the summer classification.

If there is a number followed by the letter W (SAE 20W) it means the lubricant falls within the viscosity band for 20 weight oil at -18C (0F), sometimes called the winter classification.

There is a band or range of acceptable viscosity for each viscosity weight or grade at each temperature. Sometimes liquid lubricants meet both the lower winter and the higher summer viscosity requirements, and carry numbers such as SAE 10W-30. SAE 10W-30 means that at -18C (0F) the oil viscosity falls within the 10 weight band, and at 100C (212F) the oil viscosity falls within the 30 weight band. Such lubricants are called multi-viscosity lubricants, and are made by adding specially selected VI improvers to 10 weight oil.

The viscosity of 30 weight oil at 100C (212F) is less than the viscosity of 10 weight oil at -18C (0F). The multiviscosity 10W-30 oil with VI improvers can have higher viscosity than straight 30 weight oil at 100C (212F), as illustrated here.

Should harsh service deplete the VI additive, the SAE 10W-30 oil will revert in viscosity toward the 10 weight base stock.

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#131682 - 04/28/05 01:28 AM Re: So what does "W" mean
427Z06 Offline


Registered: 12/06/03
Posts: 7409
Loc: Austin, TX
Yet another variation:

Take a particular blend of oil. Measure the absolute viscosity as you lower the temperature, -10(C), -15(C), -20(C), etc, when you reach maximum allowed absolute viscosity for the xW classification in this chart, that's first part of the grade designation, 5w, 10w, 15w, etc.

Now raise the temperature to 100(C) and measure the kinematic viscosity. Use the same chart to determine the second number 20, 30, 40, 50 etc.

So a 10w-30 would have a Low Temperature (C) Cranking Viscosity, mPa-s of less than 7000 at -25 (C) and a Low-Shear-Rate Kinematic Viscosity(mm2/s) at 100C of between 9.3 and 12.4

Digest that for awhile, then we'll explain High-Shear-Rate Viscosity and the Low Temperature (C) Pumping Viscosity, mPa-s with No Yield Stress. [Big Grin]

[ April 28, 2005, 04:42 PM: Message edited by: 427Z06 ]

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#131683 - 04/28/05 04:06 AM Re: So what does "W" mean
Dr. T Offline


Registered: 05/28/02
Posts: 2480
At first I thought.....who the **'s asking this again?

And then I see...Location: Mexico

So no wonder you're asking: It means Winter...something you don't need to worry about... [LOL!]

[ April 28, 2005, 07:29 PM: Message edited by: Dr. T ]

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#131684 - 04/28/05 04:43 AM Re: So what does "W" mean
ericgl Offline


Registered: 03/09/05
Posts: 85
Loc: Houston
The definitive answer is Winter.

EDIT: It will get you one point on the CLS exam.

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#131685 - 04/28/05 04:52 AM Re: So what does "W" mean
ToyotaNSaturn Offline


Registered: 04/11/03
Posts: 11233
Loc: Spring Hill, TN
Looks like I missed something here...how did AEHaas' name get mentioned twice in this thread when he hasn't posted to this topic yet??

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#131686 - 04/28/05 05:03 AM Re: So what does "W" mean
wavinwayne Offline


Registered: 01/06/05
Posts: 7522
Loc: North Alabama
quote:
Originally posted by ToyotaNSaturn:
Looks like I missed something here...how did AEHaas' name get mentioned twice in this thread when he hasn't posted to this topic yet??

I believe one of the links was to an article that he wrote.

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#131687 - 04/28/05 10:01 AM Re: So what does "W" mean
BlazerLT Offline


Registered: 08/15/04
Posts: 2359
Loc: Canada
quote:
Originally posted by ericgl:
The definitive answer is Winter.

EDIT: It will get you one point on the CLS exam.

IT does not mean winter or weight.

It is just a freaking letter.

And to all thinking that in a 10w30 that the engine oil is a 10 weight when cold and a thicker weight weight warm need to go back to highschool.

Since when is oil thinner when cold.

Again, W is not for winter or weight. It is just a letter.

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#131688 - 04/28/05 10:04 AM Re: So what does "W" mean
Ugly3 Offline


Registered: 08/06/04
Posts: 2635
Loc: Chicago
The letter "W" means anything you want it to. [LOL!]

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