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Posted (edited)
What does the w stand for in 10w-40 in motor oil?

 

Living life one curve after the other. Vroom scooting, thru the countryside.

 

W stands for Winter, it's the viscosity of the oil at "winter temperatures" I'm sure the actual winter temp that the viscosity is measured at will be defined somewhere. (added: the test temps are 0 deg F (winter) & 210 deg F (Summer))

So a 10W-40 oil means the oil has a lower viscosity (i.e. less resistance to flow) at winter temps than it does at summer temps. Exactly what we want so when it's cold the oil circulates easier/ quicker.

Hope that helps :)

Edited by Kretz
checked & added test temps
Posted

I am just a bit confused, for years I have known it to be weight. Everyone calls it 10weight 40 etc

 

Living life one curve after the other. Vroom scooting, thru the countryside.

Posted

In a 10w-40 for example the 10w bit (W = winter, not weight, watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature. The lower the "W" number the better the oil's cold temperature/cold start performance.

 

The temperatures I mentioned earlier are 0 deg F for "winter", the second number repeats the same test test at 210 deg F

the test is based on how long it takes a specified amount of oil to flow through an aperture. The lower the number the easier the oil will flow

 

This gives a pretty good take on the whole thing

http://www.lardoil.com/Data/Sites/16/pdf/lard-oil-tipoftheweek-multi-grade-oils.pdf

Posted

No i was watching a game show called The Wall. They asked what does the w mean in 10w-40? The answers were Water.wear,winter,weight

 

Well the lady answered weight which for 30 yrs I have heard people say 10weight 40 its always referred to as weight, long story short she got the wrong answer they just pulled a fast one and said it stood for winter! Said something about viscosity, Wow I didn't know that so I figured I would ask here but for some reason it didn't give me poll options.

 

Living life one curve after the other. Vroom scooting, thru the countryside.

Posted
I understood what you said i just had no idea!

 

Living life one curve after the other. Vroom scooting, thru the countryside.

 

Apologies Snyper, It might have appeared I was being a smart ass with the bold characters, :o I copied/ pasted that bit & I couldn't change the font :) then what I added after stayed in the same font.

Posted

So.... When do they use S for summer...?? W has always stood for weight. 20w..30w..etc. 10w-40 basically means the oil flows like 10 and has the viscosity of 40. That's my story and I'm sticking to it.... :backinmyday::icon_lurker:

Posted
W has always stood for weight. 20w..30w..etc. 10w-40 basically means the oil flows like 10 and has the viscosity of 40. That's my story and I'm sticking to it.... :backinmyday::icon_lurker:

 

That's how I always understood it and I ain't changin now neither ... 'nuff said LOL

Posted

Me neither probably confuse the people atautozone,oreily and most definitely Walmart!

 

Living life one curve after the other. Vroom scooting, thru the countryside.

Posted
That's how I always understood it and I ain't changin now neither ... 'nuff said LOL

 

Yeah, it seems like people are always trying to reinvent word definitions. I remember when gay stood for being happy... :whistling:

Posted
As long as I can remember it's been weight in relation to visicosity O too 140w. 0 being lite 140 heavy, works for me.

 

Yeah that I have a quart of 5w-20 I used on the motorcycle. I also got rid of that annoying brake squeal with it :whistling: It seems to have helped my front brake lever just dump some of that in the resovoir and it seems the weight helps push the brake fluid down.:stickpoke:

 

 

 

 

 

 

Ok so I used it on the cables, But I have seen the other 2 things done with oil...

Posted

A single-grade engine oil, as defined by SAE J300, cannot use a polymeric Viscosity Index Improver (also referred to as Viscosity Modifier) additive. SAE J300 has established eleven viscosity grades, of which six are considered Winter-grades and given a W designation. The 11 viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. These numbers are often referred to as the "weight" of a motor oil, and single-grade motor oils are often called "straight-weight" oils.

As shown above the W is for winter when its present but it is for weight when its not? freaking engineers.

 

from my research the test is a measured qty of oil is poured into a funnel with a standard sized orifice at the bottom. At 32'F (water freezes)(winter tempearture) the oil takes 10 minutes to flow through, a 20w oil would be 20 minutes and a 5w oil would do it in 5 minutes. so 10w oil takes ten minutes to flow but 10 w-30 is a multi weight oil meaning that it lubricates (stick to metal) but flows like a 10w in the winter.

 

Basically modern oils should be using DTMS designations, just like small engines should be torque rated not rated as Horsepower,and household vacuums should berated in CFM not AMPS

 

Marketing types have figured out how to use various standards that no longer have a meaning and make us believe product A is better than B.

 

a 20w 50 is not twice as good as a 10w-50 it simply refers to its flow rate at cold temperatures

 

Horse power on small engines is RPM dependent so a Briggs and a Honda shaft drive lawn more engine can have the same torque with a 21" blade but Brigggs rates there motor at 4800 rpm as 7.75 HP while the Honda is rated at 4500 RPM as 7.35 HP.

 

The AMP rating on vacumm cleaners is the max amps the engine can draw at a given voltage before it ceases to run (read explodes) However ever if motor is turning a 2 bladed fan with a 1 in 3 pitch and motor 2 is turning a 3 bladed fan with the same pitch it, Motor 2 moves 50% more air.

 

Damn pitchmen and advertisers always screwing things up

 

Now you guys got me throwing stuff around, yelling at my computer and foaming at the mouth.

:soapbox:

Posted

Ah Yes! But with your vacuum cleaner you forgot all about Watts, Power factor & motor efficiency!

An Engineer..... Mwahahahah!

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